On my work bench now...another one affected by P.O.I.T. syndrome (Point Of Impact & Tracking).

This a well built .30 cal. hunting rig that I'd previously bedded the bases and lapped/bedded the rings on. With the previous scope, it shot honest 1/2" three shot groups with hunting class bullets and a bit of load work. I've spent a bit of time behind the gun so I'm well acquainted with it. It's a good one.

Long story short, a new $1,500 scope and mounts get put on it (by a third party, not me ). Now, it won't/can't hold zero, won't/can't track and shoots patterns...like 4 inch groups.

The post mortem gives some clues. I wonder where I'll start??????

Good shootin' -Al

Wrong bases?
Different shooter?

Bases are correct part numbers for the action. The installation was fumbled and bumbled...no checking for proper contact, etc., etc.

Good shootin'. -Al

Why'd you let someone else mount your scope?

It's not mine.

Faint scuff marks at the edge of the ring base are a giveaway: Base was not securely mounted.

POIT “syndrome” …. Did they do a tracking test before it lost it ?

I understand putting better glass on a rifle - I don’t understand why the new owner wouldn’t have you bed the bases, and lap or bed the rings..


Sounds like Cabelas, Bass Pro or Scheels mounted the scope for them….

Brand of mounts, rings and scope would help.

I'm not saying that improper base fit wasn't the cause of or a contributing factor to the issue; however, I can add that I've pulled a lot of bases off that left marks like that, and the rigs actually shot tight groups while so equiped. IME, Talley LW is about the worst for action to base interface fit, but others can be shotty as well. Just the same, if the bases are screwed tight to the action so that there's no play, and, more importantly, they're properly aligned so that they're not stressing the scope, they still usually group fine. Thus, the first thing I'd do before conclusively blaming anything is independently check the rifle and scope for functionality. New scopes have given me fits before, especially those from a certain brand that has gained a reputation for not tracking too well.

I've also had bases leave marks even though the rifle shot well. This is especially true with the rough, gravel blasted, "matte" finish on some rifles like the one (no prefix M700?) that Al is working on. The rougher finish has a lot more "high points" that mark very easily regardless of how good the bluing/finish may be.

I had a Rem 700 do that, learned the front base had a larger radius than the receiver. It was the correct Leupold base number but it just didn't fit properly. Took me some time and plenty of shooting to figure it out.

Tested the scope at the range today on one of my rifles. A-B-A against the known good scope on my gun and one of my 'iron ball' test scopes that gets used to diagnose scope issues.

The scope is fine. -Al

Paul Mauser brought about the square bridge Mauser what, a hundred years ago?

Why we are using round receivers with ”dinky little 6-48 screws inherited from receiver sights" (Jack O'Connor),
is beyond me.

receivers with integral bases, that's optics mounting evolution if you want it to be........

In 20 more years, I predict that hunting rifles will come with a coupon for brawndo, and chambered only in 6.5 creed:

Don't drag Idiocracy into an discussion that also includes the 6.5 manbun

I found several years ago that bedding the base to the action took away a lot of issues. Lapping rings after bedding the bases took away a lot more.

Going back to what works.

Mount bases have the anodizing removed, cleaned with acetone and bedded to the receiver. The lapping bar aligns the setup and keeps it aligned as the bedding cures. 24 hrs. later, they are removed. Edges will be smoothed with a diamond file and the screw holes lightly radiused with a VLD neck chamfer tool. 100% contact between base and receiver:



A little light oil is all you need on the screw threads. Benelli choke tube oil works well as will a lot of light machine oils. Don't use a creeping oil like Kroil or Marvel Mystery Oil...you want to use something that stays in place:



Lightly snug, then loosen the screws a bit:



Lay the lapping bar in the rings bottoms to align the rings:



Keeping light pressure on the bar, move it forward and back so you can snug the screws. You can just see the back of the bar in this shot. Remove the bar and finish snugging the screws:



Ring lapping and bedding comes next.

Good shootin' -Al

Burris signature rings for the win!

Yes...great product.

But you still have to address the base fit issue. -Al

Al:

Am I reading it correct that you oil the mount screws before turning them into the action?

Yep. -Al

Torque values are calculated with lubed threads.

Exactly. Probably too long of a screw in the front hole. Probably making contact with the barrel threads too. And boy, that finish sucks balls... Al's doing right by removing some of it and bedding those mounts. Not every rifle needs this treatment though.

Yep. Thread lockers accomplish this as well.

I usually treat the screws with break parts cleaner to get rid of the oil and then apply a thread locker. I've found this to be especially important when using aluminum bases/mounts. Otherwise, I've experience compression of the base material overtime and, as a result, loose screws. I usually apply a coat of the thread locker under the base to act as bedding and to help keep moisture out.

If the bases fit the action contour too poorly, I try another brand.

Front screw wasn't too long...no evidence of it touching the barrel threads. Base was secure to the receiver. The finish isn't as rough as the camera makes it appear to be. -Al

In the end was the problem the Talleys rocking on the receiver?

No! yer supposed to glob it with paint that hydrolocks the screw & gives false torque readings.

Or, WAY too much Loctite that does the same, plus hampers hardening qualities of the product.

Bedding failure ?

AJO syndrome ?


Asian junk optics.

Cheap azz Remington 700 action ?

Casey, these Talley LW's are what I'm putting on to replace the previous bases.

The root of the problem was the poor fit of the previous bases to the receiver, particularly at the front. When the rings were mounted, this compounded the issue as the front and rear rings then weren't the same height...which didn't give the rings much purchase on the scope tube. Honestly, I'm surprised the scope tube wasn't damaged. It didn't take the owner many rounds to figure out things were screwed up, so that likely prevented that.

So even though everything was seemingly tight, the whole system was stressed and didn't stay in the same spot from shot to shot. This caused the horrible on-target POI changes from a very accurate hunting gun.

Ring lapping comes next.

This is after 5 strokes with the lapping bar...just to see where we're at:



Another 10 strokes...almost there:



A few more and we're done. We've removed enough to allow for a good layer of bedding:



Good shootin' -Al

Ring bedding pre-clean up.

Good shootin' -Al

Do only Asian scopes require glass bedding ?

Let me look in my Chrystal ball....

After you glass bed the scope the accuracy problem is going to just mAgically disappear.


Ps......that is some goofy chit Al.

The Talley LW rings are narrow at the parting lines...which is the main reason they break. If this isn't addressed, the rings are under a lot of stress when tightened. Same goes for the bottoms. Talley has definitely made some changes in this area as the 4-5 sets I've gotten in the past year aren't as 'tight' at the parting lines as previous ones. Sometimes the tops need bedding too but on this set, a light lapping brought the parting lines around. After a light bit of file work to chamfer the edges, a little Prussian Blue confirmed that the tops were making excellent contact with the scope tube so further lapping and bedding wasn't required. Finished up the chamfering after this pic and put some Aluma Black on the inside ring tops.



Looks like a break in the weather coming for Tuesday so I'll get it to the range to confirm the work and reset the zero.



This gun (top) is the 'big brother' to my personal 250 Ackley (bottom).



Always something to do!

I like your gun room.

Neater than mine, for sure.

DF

Just like mAgic....

Thanks...appreciate it.

If I get too many things going at once, it can look like a S.W.A.T. team threw a flash-bang grenade in there and closed the door!

Good shootin'. -Al

I'm sure I'm not the only one looking forward to the report on how that rifle will now shoot.

very nice gun room for sure.

Thanks Al for taking the time to explain the issue! I appreciate it.

Al:

I give you credit for working hard to get the most out of the Talley LW design. Once you get them smoothed via the lapping process, have you experienced scope shifting?

I agree with your assessment of why some were prone to cracking. I received a few sets that were very egg shaped. Talley claims that this was a deliberate design feature, but I never liked the thought that tightening the rings around the scope was supposed to force them into round; always figured that's a lot of extra stress on the assemblage. I treated a few sets similar to what you do, but then found I was experiencing some scope shift in higher recoiling set ups. Finally had 2 ring caps crack, so moved onto different rigging. They do make for a nice looking set up though.

Starbuck: Once worked over, I've yet to have any scope shifting issues. As to recoil levels, the biggest stuff I have them on are a couple of 300 WSM's. a 300 WSM based wildcat and a 7 MM Dakota...the 7MM Dakota is a bit of a horse for recoil.

I agree with you on the 'egg shape'. Here's a good example of this on a set I did some time back. With a ground lapping bar in place, the tight parting lines are pretty obvious. This keeps the scope tube from being supported by the ring..it has to be forced down to the bottom of the 'ring' by the pressure being exerted on the scope tube from the wedging at the top.bottoms parting lines. This also pinches the scope tube and puts a lot of stress on both the top and bottom screw flanges. Just a matter of time before they go 'pop'.

Nothing you don't already know from having worked these over. But it may be instructive to others that are looking at doing this.



Same rings after being lapped and bedded. You can just see the bedding compound under the bases.



Thanks for the input, sir. -Al

Al
I bed under the base even under pic rails, and lap the rings, but have not bedded a scope in lapped rings. Do you see a big difference by bedding the scope?
All my issues have gone away by just bedding the base and lapping the rings.

Al:

Thanks for the answer. The rigs I experienced scope movement in Talley LW on were a Weatherby ULW in 7mm WM and a lightweight 338 Win mag. Both have significant recoil that is very sharp in nature. The scopes involved were Leupold 2.5-8's, so not even as much inertia as you'd experience with the heavier scopes more commonly in use these days.

The light 338 in reference has killed a few scopes and broke a few iterations of mounting/ring set ups. I credit it with greatly enhancing my scope and mounting systems durability knowledge; had to keep researching and trying different things to get something that would hold up on it.

Seems manufacturing processes on guns and scope mounting accessories are getting much better these days. I still check alignment of everything with a lapping bar, but I rarely have to grind anything. I do use a lot more rails these days, which obviously helps with alignment.

Good luck out there. Let us know how the job worked out.

Al:

What type of bedding compound do you use for the bases (and the rings, I assume). Also, if you want to change bases and/or rings (i.e. for a scope change), how difficult is it to break the bedding bond and what can be used to remove the bedding material itself?

So, Al...have you tested the rifle in the OP to verify that the scope mounting was the root cause of the problem?

I guess it depends on how far out the rings are. A quick pass with the lapping bar will give a good indicator of where things are at. l simply bed all the rings at this point. No work and a little bit of time and then you know stuff is right. I'm not much on guessing or hoping stuff is right.

Here's some recent before/afters for example:

Interarms Mini Mauser:









Sako A1 single shot 22PPC:







Kelbly/Davidson BR 3/8" dovetails get the same treatment:

I tested the scope from it on one of my other guns and it checked out fine.

One of my test scopes is on the gun now...just to make sure. Will swap scopes at the range if that looks good. -Al

For bedding the bases, I use Pro Bed 2000. But I've also used other brands in the past with good results. I'd advise not using anything with a metallic component, though. The bases are not epoxied to the receiver....the epoxy simply makes for a perfect mating surface between the bases and the receiver.

For the rings, I like Acra Glas Gel or Pro Bed. Don't use anything too 'hard'...like Steel Bed, for example.

Hope this helps. -Al

Here's the 'problem target' shot after the new scope and mounts were installed.

This is three, 3 shot groups at 200 using the same aiming point (center of target) for all three groups. Everything strung out vertically at random. This is from a gun and load that routinely shoots 1/2" three shot groups at 100 and and a bit over 1" groups at 200 with 180 Accubonds.



With my handmade 150gr. flat based BR bullets, it's scary accurate!

Looks like that rifle's a shooter for sure, Al, but what I'd like to know is whether that second pic is a target shot after working over the mounts and rings...or have you not shot for verification yet?

I'm interested for my own purposes, not to pick nits.

The .253 group is from when I did the initial load workup after putting the rifle together....posted to show that the gun is a known-good rig. My Dakota B-1 150 gr. flat bases are what I use as a 'standard' when initially working with a mid to big-ish .30 cal. hunting rig. If a gun won't show you something with these, it's got problems!

This where I ended with for a hunting load and what's been shot in the gun ever since....180 Accubonds over 61 gr. of H4350 and a Winchester LRM primer. Solid mid -1/2" three shot groups are pretty routine with this load in any sort of decent conditions. This load is what was shot on the 'problem' target posted above.



Will get it out tomorrow and see what happens. Load will be the same 61.0 H4350 and 180 Accubonds.

Good shootin'. -Al

I'm guessing the gun in question is not a really light weight gun.....if it is not why would you run cheaply made aluminum one piece rings and bases on it ?

This morning, the winds were 16-18 mph from the 10 o'clock position with a bit of gusty tossed in. Set out wind flags at 10 and 70 yds. and hung a target at 100. With one of my test scopes on it, a three shot group measured .521.

Took my test scope off and mounted the Swarovski 3.5-18 on it. This was the new scope that was mounted with new rings and bases that led to the issues. I had previously tested the Swarovski on one my own rifles and it performed fine. After bore sighting and a couple to center things up, target #1 was shot. Let the barrel have some cool down time, gave the scope 1 click 'up' and fired target #2.



This is as good as the rifle has ever shot with this H4350/180 Accubond load.

To to close the loop on this, everything is the same except that the scope and mounts have been properly done to ensure 100% contact and to eliminate any stress.

Was this an extreme example? Yes...by all means. But it was as good a time as any to document this approach. Quite honestly, I initially suspected the scope as I didn't see any way the mounting setup could be so bad as to cause that kind of change. No need to name the maker of the bases and rings that were initially installed....they are a quality product. It's a bad mounting job and not paying attention to details that caused this. No doubt the original mounting system, properly done, would have done a very good job.

And things don't have be this extremely wonky to still give problems and give opportunities for improvement. Given that the scope tracks well and holds POI, a rifles accuracy and POI ability to hold zero are all about consistency. For the serious hunter and rifleman, bedding bases and rings simply gives you that extra bit of consistency.

Good shootin' -Al

P.S. The Swarovski 3.5-18 has great glass and big sweet spot of parallax correction. One annoying thing is that the w/e adjustments are close to 1/2" at 100 yds., despite what the turrets say. That's been an Swarovski tendancy on every one of their scopes I've been behind, including a prototype 36X BR scope that had close to 3/8" of movement rather than 1/8".

Again, good stuff Al. Thanks for taking the time to post the info.

Good write up and photos, thanks for taking the time to do this.
I have bedded bases for years and lapped rings but never bedded the scope. Something new to look at.

Early on, I'd bed the scope I was going to use in the rings. As things evolved, I began mic'ing scope tubes and found that 1" tubes ran the gamut from .995 to 1.003. I've since settled on bedding the lapping bar. If you do this and use a bedding compound that isn't too 'hard' (relative term), the scopes rings become universal for any scopes in that family of tube size. That's why AcraGlas Gel is my go-to for bedding rings.

The late Norman E. Johnson put me on to checking tube diameters. At first I was skeptical but after checking a couple dozen I found out he was correct. Norm was one of the first guys doing this and writing about it. His work on this and also on properly bedding the action was very, very helpful to a young guy like me looking for guidance.

Good shootin'. -Al

Al,
Any comments on the practice of using rubber cement inside the rings?

Some good info here.Thanks for taking the time to give us a tutorial!!
Maybe the Bossman could make it a sticky.

I've only done it twice on a couple of bigger guns. One was a .338 Mag. Model 70 and the other as 700 Custom Shop 375 H&H. Both had bedded and lapped Leupold Dual Dovetails and the rubber cement was insurance for slippage since both have gloss Leupolds on them. Neither had issues...which may or may not say anything about the rubber cement. -Al

Thanks for sharing this info. I will definitely start going a little deeper when I’m scope mounting.

Ditto. Thanks Al.

Al
So you are bedding the lapping bar and not the actual scope?
I started bedding the bases after mic'ing several 700 actions and found they varied in diameter as well. And them there is the issue to the 2 different radiuses from front to back, not to mention if you are using a one piece base that there is almost always a gap if you hand one end of the rail firm against the receiver.

Might be why back in the day most everyone used and recommended using the Redfield or Leupold one piece scope base.

Two piece bases were out there but not many people used them. No doubt the one piece base is stronger and more stable than a two piece base. What amazes me is the faith people put in aluminum rings and bases.

Aluminum is a good material for beer cans and custom wheels....I want steel for scope bases and rings.

Correct. The lapping bars are 1.00 and 1.181 (30mm) and are ground rather than turned. If you're going to make your own out of round bar stock, make sure on the dimension as that can vary quite a bit. Both of mine are home made...drilled and tapped them 3/8X16 and Loctited a carriage bolt with a piece rubber hose around it for a handle. Permatex valve grinding compound works great for a lapping compound. When the bedding is in the ring bottoms, I just lay the lapping bar in the bottoms with the handle supported by the side of the stock. I used to put the ring tops on but you have to tighten them a bit more than I like to keep the bar from rotating in the bedding material. Laying the lapping bar in the bottoms just seem to work better for me. This is a Sako A1 single shot 22PPC I did recently:












Yep. Most of the ring/base mfgs. stuff is pretty much on for dimensions. The ring/base mfgs have no control over what dimensions the actions are (any make) and that's where the tolerances start to stack up. Up until 2006, The 700's weren't ground or tuned on the O.D....they were hand finished, except for the 40X's, which were either ground or turned for roundness and the rear bridge was profiled.

Good shootin'. -Al

Nice Sako Al....I wasn't too impressed with Leupold's attempt at mating up with a Sako dove tailed receiver.

Buehler made a base that allowed the use of their rings on a dove tailed Sako receiver...when Tally came out with a Sako base for the dove tailed Sako receiver I converted from Buehler to the Tally base and rings on my Sako's.

Very informative post as usual Al. Thank you.

For years I used Warne rings directly to the Sako/Tikka integral rail. Due to reports of vertically split rings adversely affecting scope tracking, the last couple Tikka I set up were done with the Sportmatch rings that have been widely recommended here and on other sites. Both options have been fantastic, and through numerous set ups I've yet to encounter a pair of either that required any lapping for alignment. Both options hold a scope securely and don't leave ring marks or marring on scope tubes.

When available, I like to mount directly the the integral receiver rails or bases. Unless adding inclination, I don't see the utility in adding extra screws and parts to the assembly; often times it puts the scope up unnecessarily high, and it adds more things to go wrong and more parts and surfaces to be off a little and require attention.

My lapping bars are drops from Thompson shafts from back in my tool and die days. Can not drill those for a handle as they are as hard as a wedding night pecker. My 1" is about 12-14" long and I just wrapped electrical tape around each end to prevent scratching anything (after I scratched newly finished Sako, I think I threw up a little over that one)

Good to know....the next time I get a Sako to do, I'll try a set.

The best rings I've found for the Sakos have been the Leupold versions. The fit to the integral tapered dovetail is excellent and of the 5-6 sets I've used, none has required much metal removal with the lapping bar to get them squared up and aligned. This is the set from the Sako pictured earlier....you can see how much contact the lapping bar made after only half a dozen passes. Very good, especially for a steel ring.



It's one of my favorite guns...shoots killer good for a factory gun with only pillar bedding, load work and excellent hand made BR bullets.

Beautiful set up, AL.

I used the Leupold rings for Ruger's, Sako, Tikka, as well as for DD and STD bases for years and had mostly good luck with them. I did experience some scope sliding and a couple broken ring screws on heavy recoilers, so I moved to 4 screw per ring designs both for extra width to grab the tube and for fastener redundancy and increased force distribution.

I know I could use smaller/less velocity calibers and or heavier or braked rifles and likely mitigate a lot of the scope and mount related issues I've experienced; however, a guy likes what he likes. As Elmer Kieth wrote, "I like to do my hunting before the shot."

As mentioned before, everything gets bedded. Did these yesterday for a pretty unique project. -Al



Finished bedded bases....pre clean up, hole chamfering, edge relieving, etc.

You're a bedding fool Al.....

I told the guys here about bedding rings and bases for a couple years now… and the guys here thought I was nuts, so I’m glad someone finally spilled the beans.

Nice pic’s Al, you must use the same release agent I use, I can see the metal finish showing in your bedding work.

What amazes me is people think this is some sort of voodoo. Or worse, that's it's either foolish, not needed or doesn't have benefits. Basic, sound mechanical priniciples are just that...basic.



It's the release wax from Score High that comes in the Pro Bed 2000 kits.

Thanks and good shootin'. -Al

Side note - I’m planning on building a 30 BR next year to shoot 100 - 300 BR with, I’m still trying to settle in after my move so I haven’t had time to screw with it yet.
I’ll use a Robinette reamer but I may go a tad thicker on the neck.

I doubt I’ll post about that here, maybe a couple pictures.
I’m still deciding on the action, stock, ….
I already haven’t NEO rest, and a good bench spotter, but need to get a good rear bag.

Some guys have recommended I look for a used rig.. but I can build one so that is hard to do.
I was looking at getting a Neuvo but …. I’m holding on right now

Good to hear. The 30BR's are so simple and work so well. Assuming a proper twist for the correct bullet lengths you're using, the only place to get in trouble with them is on the reamer specs......specifically neck diameter, neck length and free bore diameter. Those are critical for making these 30BR's work. Be aware that many of the 'Robinett' reamers are not correct, dimensionally! There are some subtle changes to better work with current Lapua 6BR parent cases that will keep you out of trouble. Feel free to contact me if you have any questions.

Randy and I are good friends and talk several times each week, usually on some project we're collaborating on. I just finished doing a pillar bedding job on his Savage 99. Now that was an interesting project! Was going to post the pics of it here but thought better of it for a lot of reasons....as some of the comments here and on pillars and pillar bedding clearly illustrate.

Just finished this 30BR for myself late this Summer. Modified the Panda to a bolt in, adding a recoil lug to it and doing some other tweaks, as well.





Veered off course a bit so better end with a relevant pic of the topic. The rings are bedded....



Good shootin'. -Al

They're are still people that think it's some hoodoo..... me included.

Yeah I’m not impressed with the reamer maker marketing practice of slapping Robbinett on their reamers….
I think that finally managed to bother Randy , given he finally had to post something about the variations in spec’s.

I haven’t pinged Randy yet, but IIRC he said the only thing he’d do to his original spec was possibly go with a slightly larger neck diameter, I tend to like a thicker neck wall than most, but since I started using a arbor with a pressure monitor on it … well that’s been changing.
Historically I’m a tactical shooter, but like others once you can put them inside a dime, you want to make them clover leaf, now that I’m there I want a single hole…. But that requires hanging out with a bunch of bench shooters, so it’s now a goal for the upcoming next few years.

I did see your articles on Twist and bullet weights for 30BR assuming you are the Al I’ve seen over at accurate shooter that is…

Guilty as charged. Sent you a PM with reamer info.

One of todays projects. There might be something to this lapping and bedding stuff.....

Reupold's excel at lapping. Hint.



Last rifle hastily assembled,on tail end of last pass. James' spout(7" RPM 224 Speedmire),90 Beer Can Smooches at 3225fps from 22",Alpha brass,'17',TT Flattie trigger,REAL M40A1 Return,1913 base/rings,10x MQ. Seems to shoot a "smidge",despite dragging Wichita's in the process. Hint.




TQ values would cause Nightmares,scritches,scratches and a dose of weather,being givens(fhuqking POURING now). Rifles shoot loose and NEVER tight. Hint.

Have a few more rifles enroute,but it's tough to ascertain timing,given the weather. I see a new barrel in an unopened parcel and more than a few others packages to carve through. MTU 280 oughtta be close too. Hint.....................

Who can I pay to bed my scopes? Grin

Tell un Big Stick....

Where do you get those red barrel condoms ?

Black electrical is cheaper hint hint....

I was running to an Eye Exam when I talked to you in the store this morning and I forgot to grab some '33,for a certain .284" and 190 Beer Cans. Need to double back and check Mail,while yarding same home.

Typically,Base Manufacturers do a suplizingly good job,in regards to concentricity. Rifle Makers drop ALL sorts of balls,in regards to same,especially amongst those with differing bridge heights by literal design. Those woes ain't a Lapping Party Fix,thus the affinity for eccentrics and their stalwart sanctity. Nice to eek inclination,unbind a tube and bolster internals,all at the same fhuqking time. Everything below zero on the erector,is 100% fhuqking USELESS. Hint.

Pass The 'Horn Rings and hold the fhuqking Fluff,even if you gotta fire up a 'Horn File,for non 1913 bases. Hint.(grin)





I WANT "crooked" bases,because that's how inclination is garnered. Hint........................

What good comes from bedding two piece scope bases with out some way to check and see if they are dead level with the bore ?

Fact your bedding voOdoo might even push the bases off pefect level with the bore.

Bedding a scope lapping bar to your rings is a little tOo much fluff....

Why bother lapping just bed ?

Too much hoOdoo for me...

We sent a man to the moOn years ago no discoveries left for yOu Al.

LFC The bases will contact the receiver as before bedding but any space or void will be filled by the epoxy providing 100% contact hopefully eliminating any movement.

I had a SBE 1 drilled and tapped for a scope 20 years ago....when I picked the gun up the gunsmith had bedded the Talley bases to the action.

The bases on a SBE don't come close to making full contact so he went the extra mile and epoxied them on.

Problem I have with the base bedding claim is it fixing an accuracy problem....if a base after being lock tite'd and torqued in place rOcks and rolls on the action you have bigger problems.

It’s not rocket science it’s simply good practice to have materials mate (fit) correctly.

The other thing - Ring marks - if you bed your scope in the rings with bedding compound the likelihood of leaving a ring mark is about zero … unless you are using steel rings with 3 or more screws you can’t put enough pressure on a well fitted ring to bend the tube.

Personally I like bedding rings MORE than lapping them extensively…

Most precision shooting type smiths (not table top gunsmiths) know about bedding rings… so just ask them if they can do it for you.

There's few things more "HORRIFYING!" than a "dreaded" "mark" upon one's scope tube. Give or fhuqking take. Hint.

60 MoMo's inclination,(5) base fasteners,(12) ring fasteners,likely some nail polish,perhaps some tape and mebbe even a DREADED "scratch". Hint. Fhuqking LAUGHING!




Shot (1) group on 100yd paper,then rallied it,like you "get" to read about. Hint.




FooFoo Fluff Fhuqkery really ain't my jam,mainly because I actually fhuqking shoot. I assuredly love Al,but I've personally puked (8) sets of LW's and everyone I know who actually shoots,has puked a set. Though admittedly,these ain't Bench Queen Affairs or Haybale & Crockett "Adventures". Hint.






'Horn Rings are THE greatest gift one can hand a scope. Conjoin same with a ruggedly reliable base and glass that'll stubbornly retain zero,track and repeat and schit gets pretty fhuqking easy,pretty fhuqking QUICK. hint.






I reckon it's easy for me to say,if only because I shoot it all and then some. Hint..........................

Bigstick looks like some critter chewed your muzzle condom.

'Stick...now you're makin' me blush!

These cured yesterday....square bolt, light weight rings for .180 cross slot Weaver bases. Properly bedded, they have more contact area on the scope tube than rings double the width. Full contact, no stress goodness!



Even my Kelblys and Harrels get treated:



Just finishing up this little 'bedding job' too...refitting a glued-in sleeved Remington to a pillar bedded bolt in:













Stay warm up there, buddy! -Al

-21 at work and 50 at the house,for a nice ambient swing. Hint.(grin)

I'm awaiting an MTU 280,(4) Seex Kreed Waypoints,a 357 Lever Gun and have a new 7" RPM 223AI James spout to toss aboard sumptin'. It's rough..........................(grin)

This Savage 12FV recceiver was a real mess. On the good side, the receiver was at least round and the same diameter front and rear. The bad news....the base mounting holes were neither aligned with the 'X' axis or aligned with each other....the front pointed 5 degrees one way and the rear 3 degrees the other direction. After establishing the center line, opening up the 6-48 screw holes to 8-40's took care of the misalignment so at least the base mounting holes were aligned with each other.



You know what happened next.......







You can just see a hint of the bedding under the bases.



With the w/e adjustments centered on the scope and bore sighting down the barrel at 100 yds, the first shot at 100 yds. was 2" high and about 2 1/2" left. Pretty good alignment, considering the Savage barrel nut lash up.

Good shootin'. -Al

I'm not seeing any recoil lugs on those bases hope she's not a hard kicker...

Keeping rings from moving on bases....not much of a hill for even an average climber. -Al

Al, you’d better be judicious with that Acragel, Brownells hasn’t had any in stock for 6 months now……😊

Yeah....they do have the 64 oz. resin and hardener in stock but for my limited uses of it, it's a bit much.

Sourced some powdered Nylon from a pal that uses it in his 3D printing business and have been experimenting with mix ratios in the Pro Bed for bedding the scope tubes. My Panda pictured above was the first time I used it....seems to be right on the money for the characteristics I want for bedding the scope tubes.

Have a great Thanksgiving! -Al

tag

The Grapevine notes a MTU 280 shipping today,though the weather ain't gonna do The Pony Express any favors. This Kansas Dust is tough on transit! Hint.




LAUGHING!

Shout when the brass makes it to you,so I can scratch it offa my radar..................

Will do....appreciate the thoughtfulness on your part, man.

I'll tip one of these this evening with a nod your direction and say: "Ich weiß es zu schätzen!" ("Thank you. I appreciate it.", in German) -Al

Why am I not surprised you drink peanut butter whiskey...

You call that a group? Why aren't they all touching? Did you call those flyers?

It’s nice to have all of these remedies available but I’ve got the Talley lightweight rings holding my Zeiss HD5 on an old Vanguard 300 Weatherby going on 7 years a few hundred miles of NW Colorado oak brush, trees & rocks still holding zero. Two shots - one elk 1 deer about 40 miles of brush trees & crap taking the finish off scope & rifle - maximum loads of IMR 4350 pushing 180 grain Barnes about 3200 FPS. This & 3 other 300 rifle varieties with different scopes no issues.

My Dual dovetail mounts held when my son dropped my favorite 7 mag directly on the Leupold 4.5-14x50 bell from about 5’. Unfortunately the scope didn’t fare as well. I’ll check in next week but likely going back for repair. Shot 1 ragged hole before the drop.

It’s nice when stuff keeps working

Tag

Al.
Thanks for all the advice and demonstration in this thread. I was following your instructions to the letter on a SS M70 .270 WSM that I was swapping the mounts for Leupold Backcountry. The bases looked like they were a good fit, but I bedded them per your instructions, and it turned out they were really not in good contact at all, only touching at a couple of "strips" on each base. From now on I will plan to bed them all.
I lapped the lower rings, as I knew they were both tilted towards the center of the receiver from previous measurements of the receiver and shimming previous bases. I was about to bed the rings using the Wheeler lapping bar, as you advised, but decided to measure it first. Though my scope was spot on 30mm at 1.181", the lapping bar was .006" under this, and I was afraid it would make too tight of a fit. I throw this out as advice that everyone ought to measure the scope and the bar in making their decision. Given my disparity, with a bit of trepidation, I spread some release agent on my scope and pushed it into the Acraglas Gel. Since it lacked the weight of the lapping bar, I added a couple rubber bands to keep just a little pressure on it while the glass cured. It turned out fine, with the rear base just perfect, but I suppose I did not press the forward one down hard enough as I had thicker cured gel here, and a little bit of a void. I went ahead and cleaned everything up and mounted the scope. Do you think this'll be OK? Take a look at the last attached picture. Looked pretty well supported overall so I let it be.

Thanks again,
Rex

Over a decade ago, you posted [aka NOBODY] about ring lapping and lap dancing.

I believe no one changes their mind through facts or analogies. But fear or being laughed at CAN move the needle.

To make fun of them, enter their frame of reference and embrace it in a ridiculous way. You have done that.

All I can offer is my calculation about 30-06 recoil force on scope mass meets the low coefficient of friction when oil gets between the receiver and scope base.

Maynard Beuhler took minute scope tube diameter differences into account when he designed his shimmed scope rings.

I suspect Beuhlers design was well before the writer that wrote about it Al.

Was it Big stick that said "Man can not live by lapping bar alone...."

The line up bars with the sharp little points will show you more than the lap dancer.

Oil...

Wonder if that same oil over time degrades the little smear of bedding compound they're putting between their scope rings and bases.....

Damn if you do damned if you don't.

Most ring marks are caused by improper scope mounting....I suspect Big Stick knew all that.

Hint......hint...hint....

Hint

You are an idiot

Jim Sweet should have coached you on manners....


Punk

I used to think this too, then I learned that the two line-up bars with their sharp points can be out of alignment in angle and the points will still line up. This is especially important when using them for their original purpose, "turning in" the front ring on Redfield Jr style bases (or both rings on Dual Dovetail bases).
Think about it - if the rear ring (the one with the windage adjustments on a JR/SR-type base) is not perfectly aligned with the bore, and you mount the one bar in it, then turn in the front ring until the second bar's points line up, that doesn't do anything to insure the two bars are parallel and aligned. In fact, if the rear ring is centered over the bore but misaligned off bore axis, the front ring has to be equally misaligned in the opposite direction for the two tips to line up. If the rear ring is aligned with the bore in angle but offset to the left or right because the windage screws are not perfectly centered, the front ring has to be misaligned in angle to the opposite side of the rear ring's offset.
I think it was Mule Deer who pointed out in one of the GG chapters that it's really better to use the flat ends of the bars for aligning turn-in rings, as at least then you can see that the flats are parallel, meaning the two bars are also parallel. Having set that, then the rear base can be adjusted left or right until the two bars are aligned.
But regardless, I don't think anything will indicate misalignment better than a single known-straight bar of the right diameter laid into both rings. Take a look at the attached: If I had clamped two pointy alignment bars into these Leupold Backcountry bases after they were bedded and torqued down, the points would have lined up fine, even though both bars were misaligned by a small bit in angle - in this case, both sloping slightly "downward" towards a point between the two bases. But two strokes of the lapping bar showed (as I already knew from having to shim the previous bases) that both ends of this receiver have a slight slope towards the middle. The pointy tips of line-up bars would not have shown that.

Respectfully,
Rex

One note - after you bed Correctly, the screws should abruptly come to a stop vs tensioning up over 10-30 degrees of turn. This occurs because you have taken the “crush” or compression factor out of the contact points.

I noticed that. Thanks for the point-out. If I had not measured its depth, it would have been easy to misinterpret this as the front-most screw bottoming on the barrel threads.
Rex

Rex, it looks like you've done a fine job.

You pic of the base bottoms show just how precious little contact there was between the base and receiver.

A little bit of a void isn't something I'd worry about. Even with a bit of a void, you'll have a better quality contact area than if you hadn't bedded. If you feel the urge to make it perfect, don't try to fill in the void as you'll end up with high spots. Best to take it out completely and redo it, if you want to go that way.

For some reason (likely ease of material availability) most commercially available 30MM lapping bars measure smaller than 1.181 . I made my 30mm bar from 1.187 stainless round stock and it's stayed at 1.181 after many lapping jobs. If yours is a bit small, just wrap a piece of high quality painters tape around it before setting it in the epoxy...that tape measures about .005 thick. Wax the tape to seal it and the wax will also act as the release agent. Measuring scope tubes can be revealing!

As you've discovered, a well done bedding job on the bases and rings acts just like a well done pillar bedding job on a stock. The screws come up to 'tight' right now. Nothing stretching or twisting and trying to conform...it's 'there' right away.

Well done, sir! -Al

Al, thanks for this thread. The time and effort you put into posting this is very much appreciated by a novice like myself.

First, great info. Thanks Al and others.

Let me throw this out there. How much does the thickness of the lapping compound add to the circumference of the bar? Could the reason they are slightly undersized be because they are taking the addition of lapping compound into consideration?

You're welcome, sir.



Possibly. I'm sure that the 1" bars measure closer simply because of material availability in that size. Either way, it's not a biggie when it comes to lapping because, as you correctly point out, the compound adds thickness anyway. The only issue is if you want to use the lapping bar as the 'slave' scope tube for bedding. But that's no deal breaker and there are multiple end runs around that small issue. That's where a compound like AcraGlas Gel works so well for tube bedding (having a small amount of conformity) rather than a hard compound like JB Weld, etc.

Good shootin' -Al

If using the actual scope instead of the bar for bedding in the rings, is there any issue with using those harder compounds like JB Weld or Devcon?

No, I just mounted a Vortex scope last week and the manual said that the specs were for dry screws and that you would need to reduce the torque if using lubricant.

In general, they seem to be a bit harder on the scope finish, with the quality/thickness of the finish being the biggest variable.

I'm a 'functional' type of guy so a few character marks doesn't bother me. One of my test scopes looks like a family of those Duluth Trading angry beavers gnawed on it. -Al

Thanks for your reply, Al. I had an epiphany after doing the job that I should have just wrapped a single layer of that wide clear packing tape around my lapping bar, and it would have been perfect. Clear tape versus masking tape due to the smooth finish on the clear tape versus the bumpy texture of the masking tape. I'm going to shoot the rifle tomorrow and see If things improved. Because the rear base ended up being nothing but a skim coat of AG Gel, and the front base had a thicker layer since it didn't get squeezed out as well, I calculate I lost 6-8 MOA of vertical range due to the minor tilt up of the scope in the rings now. If I had been using the lapping bar to bed the rings, I think I would have been more willing to press harder to get good squeeze out. So maybe I will redo it, but not until shooting tomorrow.

Thanks again for the guidance,
Rex

One more question for Al (and others).
It looks like you do not normally bed the top half of the rings - is that right?

Thanks,
Rex

It's called a half bed...

Its referred to as a half azz bed job.

Rex, it depends on how the tops fit. After the bottoms are bedded and the parting lines relieved (tops and bottoms), a bit of Prussian Blue on the tops and snugging the scope down will show how much contact you have. If it's less than 75 percent, then the tops get lapped and bedded. In the the before and after pics below, you'll get an idea of that.

The top pic is a new BR rifle I just finished late this Summer. The tops/bottoms are bedded as a matter of course as nothing can be left to chance. But I do hunting and live varmint rifles the same way. The guns couldn't be further apart in application but the goal remains the same...as much contact as possible for repeatability and no stress on anything. Instrumented testing has shown that scopes experience an average of 9 G's 'break away' loading in the instant between when the the gun fires and it starts it's rearward movement in recoil. In that instant, the scope will 'weigh' 9 times more than it's actual weight.

And In extreme cases like the one this topic was started about, you can see a shift in POI as the mounting system shakes around after each shot and comes to rest in a different spot each time....even though everything feels and looks 'tight'.

Looking forward to your range results.

Good shootin' -Al

I can see a shift all right.....

You're full of shift.

Regarding 9 G's- I'm actually pretty familiar with what that's like.

Regarding range results, I had a dramatic improvement. I have been struggling to get this .270 WSM down to just sub-MOA performance, and it has refused, with best groups just over an inch.
It's an 8" twist barrel with a long throat and a mag box that allows 3.02 max OAL. Today I took a load with the Sierra 175gr TGK that previously wouldn't break an inch. First three shots of the day from a cold, clean barrel went 0.48". Tried the 145 ELD-X, which had been in the 2" range before. Three in 0.44". See the attached.
I'm a happy camper! I plan to bed the bases & rings now on several more of my rifles.

Thanks again Al!

Rex

Well done, Rex.

My hope is that results like yours encourages others to delve into this area. There's improved accuracy and better optics performance just free for the taking.

Good shootin' -Al

Al has given good advice in this post and something for me to think about. I have bedded bases for sometime now, but not the scope.

Outstanding post, Al. I learned a lot & will certainly be going the extra mile.

While I can see the possibility of an improvement by bedding the rings my question is - would this be an improvement over the Burris Signature system which uses a synthetic insert with the pillow block arrangement?

I am not trying to start a pi$$ing contest, rather I am curious why the Burris system would not be equally good.

drover

As I mentioned earlier, the Burris Signature rings are a nice alternative for those that don't want to bed the rings.

Of course, that still leaves the bases to deal with. -Al

Al:

Thanks for sharing what you've learned and your process. Thanks, too, for always being a gentleman in these discussions.

Mostly for curiosity sake, do you regularly measure the scope tube diameters? If so, how much variation are you seeing these days?

Back in the day I used to measure scopes before I mounted them, and I did find a fair amount of deviation. If they were bigger than 1", I'd use a piece of sand paper as a shim around my lapping bar and get the diameter bigger before giving them a similar bedding treatment to what you do.

Since I've been using mostly 30mm scopes these days, I haven't found near the deviation I used to, so I've pretty well stopped measuring and just pre fit the rings to make sure there isn't an inconsistency before mounting them to the bases.

I missed that post - sorry. I have used the Burris for years and just wanted to be sure I wasn't missing something by doing so.

drover

I dont know how anyone hit anything before scope lapping and scope bedding.

Devine providence?

On newer scopes, there's certainly less variation than earlier stuff. The use of CNC centers for machining the tubes (on even lower end scopes) has certainly been a plus for consistent tube dimensions. The near universal application of matte finishes also helps as the gloss finishes of many earlier scopes varied quite a bit in thickness. No need to mention brand(s) but a couple of near-and-dear brands had tube diameters that routinely ran around .995 with extremely thin tube thicknesses on top of that. Couple those two things with less than straight and misaligned bases and there will be problems. But I always measure the tubes because I don't like surprises. For example, there are three identical, new in the box, 2-8 1" tube scopes here. Two already have homes...one on a 6.5 lb. 308W and the other on a 6.5 lb. 20 Practical fox/coyote calling rifle. All three tube dimensions are identical....at 1.010!

The hard facts are that the great majority of shooters and rifles simply aren't up to the task....so the mounting issues get lost in the noise of the overall inaccuracy of the gun mixed with the shooters limited ability. That won't win me any friends but those are the facts.

For those that want the extra accuracy and performance, it's a process that anyone with a bit of mechanical ability can both grasp the concept of and apply to their rifle. The costs are minimal and a bit of time is all that's required.

And for those that don't...hey, that's cool, too. Go shoot, hunt and enjoy.

After my wife passed away, I decided to retire early from my career in the medical field. This is a hobby for me...I don't do this for a living or a sideline and generally don't do it for hire. For me, it's about solving problems and making things as good as they can be.

Good shootin'. -Al

Al,
I have another question. You said you will bed the scope into the bottom half of the rings, but leave the top half unbedded if there is decent contact area on the scope. So when you lap the bottom of the rings to make enough room for the bedding compound, do you do it with the top half of the rings removed? Thanks again.

Thanks Al, and good shooting to you.

Correct...no tops on when the bottoms are lapped. -Al

Purely for the sake of info, here's an example of one of my 30BR chambered Benchrest guns that I worked with in 2009-2011 to absolutely hold P.O.I. and ensure tracking.

The w/e adjustments were removed and the erector tube was centered in the scope body with two aluminum sleeves. The sleeves were epoxied to the scope tube I.D. and the erector tube was epoxied to the I.D. of the sleeves. The mount was made by Gene Bukys and was a friction style adjuster with a pre-stressed beam that allowed the scope to travel.

It never so much as twitched POI or tracking!

Good shootin'. -Al

Wow. Was that a common thing to do to overcome scope limitations at the time?
Is this still done with Benchrest setups today or are scopes more up to the challenge now?

It was being done quite a bit. By and large, the move to 30MM tubes has provided the room for more robust internals...tracking and the ability to hold POI on BR scopes has definitely improved in the past decade. IOR Valdada's worm gear system and Sightron's ExacTrac were both big steps forward. -Al

Al,
Would you be willing to show a little tutorial on how, after having bedded the lower portion of the rings, you bed the upper halves of the rings? Do you remove the lower halves from the rifle and just use the lapping bar to do each ring? Or do you do the top half of the rings with the bottom halves still torqued to the receiver? If so, how do you use your release agent and masking to make sure you ONLY bed the top half of the rings, and nothing gets glued together?

Thanks,
Rex

Rex, you can do it a couple different ways. My preference is to do the tops when the lapping bar (or scope) is still in the bedded rings before it comes apart after the bedding has cured as at that point everything is aligned well. But I've gone back and bedded the tops later, too. Once the bases and bottoms are bedded correctly, everything lines up so well that it's not a biggie either way. I would caution against doing the bottoms and tops at the same time though...you want a solid base of cured bedding on the bottoms to support the small amount of clamping pressure from the tops as they are snugged down.

This is my Sako A1 22PPC:

The bedding has cured in this pic and lapping bar has not been removed. You can see the haze from the release wax on the bar and the cured bedding oozing out on the bottoms:



The tops had been lapped prior to the bottoms being bedded in preparation for bedding:



Tops after lapping:



Mold release wax over all tops surfaces except where the bedding goes....you're doing it just like the bottoms but in reverse. Put a little light machine oil like 3-In-1, etc. on the top screws. I use some Benelli choke tube oil. Don't use a creeping oil like Kroil as it will migrate into the bedding material.



Put the tops on and just lightly snug them so you get a bit of ooze. Even gaps on the ring halves is the guide, here. I had cleaned the ooze off with a plastic windshield stick already before this pic. Clearly seen is the cured compound on the bottoms and you can see a bit of it behind the back ring top also:



Give it 24 hrs and pop the tops off the bar with a screwdriver at the ring halves, chamfer the parting lines on tops and bottoms, deburr the all the edges, clean it up and you're ready to go. I always use a light oil on the ring screws, no matter what the material.

Like a properly bedded action, there's no need for any sort of torque wrench lash-up.

Good shootin'.....looking forward to your results. -Al

Thaks Al!