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Posted By: Pharmseller Help diagnose this group - 02/19/12
I shot this group today.
7mm-08
120 gr NBT
50.0 gr Ramshot Big Game
CCI 200 primers
Remington brass
Loaded 0.015" off the lands.
100 yards

[Linked Image]

The fifth shot was from a bit of a warm barrel, but as you can see I'm stumped as to why I'm getting shots touching close to 2 inches apart.

A previous 3 shot group has the same pattern, with two shots touching and a third 0.53" out.

What should I try to tighten the group?


P
Scope good?
Posted By: SodFarmer Re: Help diagnose this group - 02/20/12
I would shoot a few more groups with different charges and powders to see if you get a better result. I had a similar experience with one of my rifles and I could not find a powder or a charge that would work. In the end, I switched bullets to a different brand and the problem went away. It could be that your barrel doesn't like that particular bullet.
Posted By: rifle Re: Help diagnose this group - 02/20/12
What kind of rifle?bedded? scope? good rest? details...
Posted By: mjbgalt Re: Help diagnose this group - 02/20/12
how good was your rest? if you don't have a consistent rest you'll string them like that. use a bag under the buttstock also.
Barrel freedloated? Keep the info coming.
Good rest. Sandbags fore and aft.
Scope - Minox ZA3, Talley lightweight mounts. All screws tight.
Rifle: Weatherby Ultra Lightweight.
Not bedded.
Ultra Lightweights are supposed to like a little upward pressure on the barrel.
Not freefloated.
Fired at 6X.

What bothers me is the consistency of the inconsistency. If the scope or mounts were bad I would expect more variance.

Here's the 3 shot group I fired before the 5 shot group. This group measures 0.93" center to center. After I fired this group I let the barrel cool then adjusted the scope 10 clicks up and 3 clicks left.

[Linked Image]

P
Posted By: Tanner Re: Help diagnose this group - 02/20/12
Something you'll hear over and over again about "2 in, 1 out" type groups is to try seating in a little deeper. Lots of guys have seen groups shrink and become nice tight little triangles or clusters with that method.
Posted By: Ackleyfan Re: Help diagnose this group - 02/20/12
Base screws that are tight don't mean the bases are tight, Bases should be installed 1 screw at a time to make sure the bases are being held tight by both screws!
Originally Posted by Ackleyfan
Base screws that are tight don't mean the bases are tight, Bases should be installed 1 screw at a time to make sure the bases are being held tight by both screws!


I'm trying to visualize what you mean and it just isn't happening.

P
Need to play with the distance off the lands. With that much vertical dispersion the bullet has to be leaving the barrel midway through the cycle instead of at the top or bottom of the oscillation.
Posted By: Kenneth Re: Help diagnose this group - 02/20/12
I'm surprised people aren't jumping up and down over the

"not free-floated" statement....
Posted By: Karnis Re: Help diagnose this group - 02/20/12
Originally Posted by Pharmseller
Originally Posted by Ackleyfan
Base screws that are tight don't mean the bases are tight, Bases should be installed 1 screw at a time to make sure the bases are being held tight by both screws!


I'm trying to visualize what you mean and it just isn't happening.

P


On more than one occasion I have had Talley base screws be too long. It will play hell with your groups if the very front one is touching the threads on the barrel. To check, remove the front screw and peer down the hole with a good light. If it's too long, you will see the shiny spots on the top of the barrel threads.

That will prevent the base from seating even if you tighten it gorilla tight. Trust me on this one............
Posted By: CLB Re: Help diagnose this group - 02/20/12
Is this the same rifle you bought from Wareagle?

Maybe exchange a couple PM's w/him and see what load worked for him and start there.

Have you made ANY modifications to this rifle?

Maybe premature, but don't be afraid to remove the pressure point. After loading and shooting at least 6 bee U/L's I'll say I disagree with your logic.

Do you have your "forward" bag close to the bottom metal? or out really far? If it's too far out (close to stud) you might be placing torque on the tube.

Might also be as simple as your load combo. Do you have any 140's hanging around along with some IMR4350? if so, toss in 46 grains with 140 Nos and give it a whirl...

I'd also start my loads closer and seat deeper as/if I feel i needed to.
Posted By: CLB Re: Help diagnose this group - 02/20/12
Karnis has a very good point here and I saw the same exact thing on my pards Weatherby in 7-08 with Talley U/L's. Everything came together quick after that was fixed.
Posted By: Bowman44 Re: Help diagnose this group - 02/20/12
I agree with CLB, this seems to be a bedding/pressure issue on the action or barrel most likely. Strange things can happen, but likely its due to different pressures being put on the action or barrel or both. T.S.
Posted By: Popapi Re: Help diagnose this group - 02/20/12
I'm willing to BET THE FARM you have everything right, to say the least it's the rifle I had a WBY UL in 25-06 that did the same thing no matter what I did I COULD NOT GET IT TO SHOOT..............in turn I sent the rifle to Hill Country rifles to accurized and it came back shooting 1/2" groups with 100grn TSX...... Good luck on your rifle!

http://hillcountryrifles.com/pages/accurizing
Yep, bought it from Wareagle. IIRC he never shot it.
I'm going to check the scope mounts and seat the bullets a little deeper. I'll also remove her from the stock and reattach, paying attention to keeping the barrel centered in the channel.
I'm getting conflicting advice regarding the bedding screws. Some say tighten the rear screw first, some say the front screw first. What this tells me is there is no hard and fast rule.
I'll report back how she does. The next step (if necessary) will be removing the pressure points in the stock.

Thanks all for the help. This is kinda like watching "House."

P
Originally Posted by Popapi
I'm willing to BET THE FARM you have everything right, to say the least it's the rifle I had a WBY UL in 25-06 that did the same thing no matter what I did I COULD NOT GET IT TO SHOOT..............in turn I sent the rifle to Hill Country rifles to accurized and it came back shooting 1/2" groups with 100grn TSX...... Good luck on your rifle!

http://hillcountryrifles.com/pages/accurizing


$500.
Hoo doggy that's a chunk of change.

P
Posted By: 1minute Re: Help diagnose this group - 02/20/12
I'd suggest free floating first. If that does not help then check to see if the bedding is stressing ones action. The way I check that is to install a gridded bore sighter and note the crosshair coordinates. Loosen ones action screws and see if the coordinates change at all. If there is any shift at all, then bed the receiver in a completely relaxed state. Had to do that to a Weatherby Mark V and it came around beautifully.
Posted By: mjbgalt Re: Help diagnose this group - 02/20/12
i do it like this:

scope, then bedding. then handload shorter or longer.
Posted By: Bowman44 Re: Help diagnose this group - 02/20/12
If you look at what Hill Country Rifles is doing in their accurizing, most of the focus is on THE BEDDING and FREE FLOATING of the barrel. They do recrown and true the action and bolt face, but it would be easy to attack the first two issues without spending $500 and having to be without your rifle for a few weeks. T.S.
Posted By: Popapi Re: Help diagnose this group - 02/21/12
Originally Posted by Pharmseller
Originally Posted by Popapi
I'm willing to BET THE FARM you have everything right, to say the least it's the rifle I had a WBY UL in 25-06 that did the same thing no matter what I did I COULD NOT GET IT TO SHOOT..............in turn I sent the rifle to Hill Country rifles to accurized and it came back shooting 1/2" groups with 100grn TSX...... Good luck on your rifle!

http://hillcountryrifles.com/pages/accurizing


$500.
Hoo doggy that's a chunk of change.

P
P, realtalk MOST if not all of this can be done you or by a competent smith! All HC doing is bedding, floating, crowning, working trigger if needed etc. These are the things you MUST address on the LW to get it to perform CONSISTENTLY......... Once this was done on mine it was a wrap Guy, and then and ONLY then I really enjoyed shooting this lil rifle!
Posted By: .280Rem Re: Help diagnose this group - 02/21/12
Just my take. I had issues shooting light rifles from the bench. Found I had the snug them up a bit more than my standard wt. rifles or the groups would open up. Agree that some say, and some find, thinner contour bbls like some pressure. Before you go pulling anything apart, try shooting and snugging the rifle in a bit tighter to your shoulder. Make sure you're only pulling back, not putting any pressure down on the stock. If that doesn't help, then I'd look at the bedding and floating or making sure you don't have any unwanted pressure points.
Posted By: Savage_99 Re: Help diagnose this group - 02/21/12
Are the guard screws tight holding the action to the stock? In particular the front screw?

If they were try shooting with the rear guard loose a half turn. If that works it needs bedding.

What do the fired primers look like? Are they the same?

What does the fired brass look like? Soot on the brass?

I just shot a 243 last Wednesday with a good load at 100 yds and it made a 2" vertical group.

I found the front guard screw to be a little loose. After tightening it made a 1/2" group at 200 yds.

Of course it can be more complicated like a guard screw that bottoms out on its end etc.
Posted By: Burleyboy Re: Help diagnose this group - 02/21/12
You probably know this but, make sure you have a consistant grip on the forend and the rear of the stock the same in the bag. Make sure the sling swivels aren't rubbing on the bags. Light barreled guns show vertical really easy if your form changes slightly.

You could also try it with a business card between the barrel and the pressure points just to see if that changes anything. Definately check the Talley screw as mentioned above. I've had them too long too. 50g of big game should have pressure up there but I've had lots of vertical with some light loads of ramshot powders and huge velocity spreads. When I run ramshot a a little higher pressure things usually come together. My faux ti didn't like the Big game 120 NAB combo so I went back to RL-15.

Bb
Posted By: BobinNH Re: Help diagnose this group - 02/21/12
Good advise by others...I'd bed and float. I generally ignore the notion that a light barrel needs up pressure to shoot. If it does, I don't want it generally.Other issues crop up,like this.

If you are going to leave it bedded, at least use a softer front rest....hard, firm sandbags are sometimes hostile environments for a light tube beeded to a stiff stock....recoil forces cause the rifle to jump off the firm rest and vibrations get transmitted to the barrel, causing funky grouping,stringing, etc., like you see.

Sometimes, shooting from a softer position (like from your hands, or with a softer front rest),dampens vibrations,and the rifle will shoot better.

Floating attenuates some of this.I have seen guys with Weatherby lightweights go through the same stuff....a good bed job and floating cured it.
This is the reason I detest a buggy whip barrel...I'd float with card stock or cut up credit card and see what happens from there
Some common themes in feedback:

Check your bedding. Might check the action screws first. Two shot group usually has something moving. When you fire, the action is bouncing back and forth between two spots.

Free floating the barrel will help with this, because it will eliminate the varying pressures caused by the little nub up towards the front of the stock, and the metal heating up and expanding.

Rear screw FIRST, then front screw. I like to do this slowly and switch back and forth.

Double check your stock, and make sure it's not making contact (free floated to the lug)

I agree with those who say keep the barrel cool and check the bedding.

I can almost guarantee a vertically stringing group is due to harmonics, which are inconsistent. If you want consistency, the barrel has to be free floated, and the action screws torqued, rear bolt first.

IV) - Loose stock fixings-two groups may form from shots in any order.

� As soon as I see vertical or horizontal stringing I know I have a pet load to work with, try small changes in seating depth until you find the sweet spot. It won't be too far away from where you are at.
� Something you'll hear over and over again about "2 in, 1 out" type of groups is to try seating in a little deeper. Lots of guys have seen groups shrink and become nice tight little triangles or clusters with that method.
� Need to play with the distance off the lands. With that much vertical dispersion the bullet has to be leaving the barrel midway through the cycle instead of at the top or bottom of the oscillation.

I'd suggest free floating first. If that does not help then check to see if the bedding is stressing ones action. The way I check that is to install a gridded bore sighter and note the crosshair coordinates. Loosen ones action screws and see if the coordinates change at all. If there is any shift at all, then bed the receiver in a completely relaxed state. I had to do that to a Weatherby Mark V and it came around beautifully.

I have new mounts on the way from Weatherby (not a fan of the current mounts, plus my other Weatherbys have the same mounts).
I'll pull the stock center the barrel. I'll also seat the bullets to 0.020" from 0.015" and see what happens.

If I have the same problem I'll shim to free float and try again. If I need to I'll bed the action.

P
Posted By: CLB Re: Help diagnose this group - 02/21/12
P,

You have a ton of good advise here. But, I'd like to ask a couple of questions.

In your OP, was that the only load you tried? and how many groups gave you the vertical stringing?
No, not the only load. Other powder combinations with the same bullet were erratic. I tried some 140 gr Partitions and was very surprised at how poorly they grouped.

P
Posted By: CLB Re: Help diagnose this group - 02/21/12
Something is binding up somewhere. You sell drugs, so write yourself a script for a bedding and float job.
Posted By: 1minute Re: Help diagnose this group - 02/21/12
Just a thought if one shims with card stock. One should shim both the tang and recoil lug to simmply lift the action in ones stock. A shim in only one position will probably stress the receiver unless the card dimensions just happen to luckily compensate for a bedding issue.
Why card stock and not metal shims?
Posted By: pdkillr Re: Help diagnose this group - 02/24/12
I had the exact same problem. Barrel was rubbing on swivel stud on factory stock when it heated up. Put a Hogue stock on it made sure barrel was free floated all the way to the recoil lug by sliding a dollar bill up to it. Now the thing shoots MOA with anything. Didn't bed the action aor anything else just did a trigger job. My 2 cents.
Originally Posted by Pharmseller
Some common themes in feedback:

Check your bedding. Might check the action screws first. Two shot group usually has something moving. When you fire, the action is bouncing back and forth between two spots.

Free floating the barrel will help with this, because it will eliminate the varying pressures caused by the little nub up towards the front of the stock, and the metal heating up and expanding.

Rear screw FIRST, then front screw. I like to do this slowly and switch back and forth.

Double check your stock, and make sure it's not making contact (free floated to the lug)

I agree with those who say keep the barrel cool and check the bedding.

I can almost guarantee a vertically stringing group is due to harmonics, which are inconsistent. If you want consistency, the barrel has to be free floated, and the action screws torqued, rear bolt first.

IV) - Loose stock fixings-two groups may form from shots in any order.

� As soon as I see vertical or horizontal stringing I know I have a pet load to work with, try small changes in seating depth until you find the sweet spot. It won't be too far away from where you are at.
� Something you'll hear over and over again about "2 in, 1 out" type of groups is to try seating in a little deeper. Lots of guys have seen groups shrink and become nice tight little triangles or clusters with that method.
� Need to play with the distance off the lands. With that much vertical dispersion the bullet has to be leaving the barrel midway through the cycle instead of at the top or bottom of the oscillation.

I'd suggest free floating first. If that does not help then check to see if the bedding is stressing ones action. The way I check that is to install a gridded bore sighter and note the crosshair coordinates. Loosen ones action screws and see if the coordinates change at all. If there is any shift at all, then bed the receiver in a completely relaxed state. I had to do that to a Weatherby Mark V and it came around beautifully.

I have new mounts on the way from Weatherby (not a fan of the current mounts, plus my other Weatherbys have the same mounts).
I'll pull the stock center the barrel. I'll also seat the bullets to 0.020" from 0.015" and see what happens.

If I have the same problem I'll shim to free float and try again. If I need to I'll bed the action.

P


Man, I've been working 10 hours a day 6 days a week lately or I'd offer to take it and get it shooting good for you..... frown
Originally Posted by mjbgalt
i do it like this:

scope, then bedding. then handload shorter or longer.


Other way around. Cheapeat option first. Need to establish if it it a loa problem before soending money on the scope or rifle.
john
Originally Posted by AussieGunWriter
Originally Posted by mjbgalt
i do it like this:

scope, then bedding. then handload shorter or longer.


Other way around. Cheapeat option first. Need to establish if it it a loa problem before soending money on the scope or rifle.
john


John,
I like how you think. My son says I'm cheap, I prefer frugal.

P
Posted By: GF1 Re: Help diagnose this group - 02/26/12
Good advice here. Assuming that the rifle passes all of these checks (guard screws tight, per instructions above; bases, mounts tight; scope known good performer), if it still doesn't perform, I'd do a "poor man's" floating job just to check.

Put a piece of credit card under the front action ring, just aft of the recoil lug, tighten guard screws, front first, ensuring some downward pressure from barreled action against stock lug mortise (to ensure that the back of the recoil lug is bearing against stock). If there's a problem with the bedding, or simply if the rifle likes a free floating barrel, it will show up on your first couple of groups. If this tightens up the groups, then it's a simple matter to glass bed the rifle and free float the barrel permanently.

If this doesn't do it, I'd shop for a new rifle or barrel.
Originally Posted by Pharmseller
Originally Posted by AussieGunWriter
Originally Posted by mjbgalt
i do it like this:

scope, then bedding. then handload shorter or longer.


Other way around. Cheapeat option first. Need to establish if it it a loa problem before soending money on the scope or rifle.
john


John,
I like how you think. My son says I'm cheap, I prefer frugal.

My PC had a coronary si I pretended I was still operational on my phone. Apologies for the typo's.
john

P
I put new rings on a couple of days ago. Talleys from Weatherby (I like the W on the side).
I'm going to load some rounds tonight and try to get to the range Saturday. I think I'll seat the bullets a bit deeper, too.
Let's hope she tightens up.

P
Posted By: Azar Re: Help diagnose this group - 03/02/12
I'd suggest starting by changing one thing at a time so you can be sure of what was causing the issue.
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