I don't want to turn or ream necks, just sort them and toss them.

Can I get by with a plain old ball micrometer? Do you just spin the brass on the micrometer and get the readings? What is your keep and toss measurement?

Sinclair sells a pretty nice bench top unit (~ 75.00 without pilots), but you have to buy pilots.

I can get a decent ball micrometer for under 50 bucks.

I've been around that block.

For sorting and tossing do yourself a favor and get the Sinclair or Redding tool that uses pilots and a dial indicator.

mathman

It is the neck wall thickness that varies, just turning the case and measuring the OD ,isn't going to tell you much

No, I am talking about neck walls as you stated.

Just found the Redding on sale and ordered it. Looks to be a great price, and a real sale, not $1.00 off..........

http://www.midsouthshooterssupply.com/item.asp?sku=0007626400

Found out about the sale here:
http://64.233.169.104/search?q=cache:OxDnMmIKaUEJ:www.6mmbr.com/casenecktools.html+how+to+measure+case+necks&hl=en&ct=clnk&cd=2&gl=us&client=firefox-a

Mathman- any of your usual good tips on case prep are appreciated per using this tool. I got the Sinclair concentricity gage, and had to bring it up a notch.

You'll find that a lot of the neck runout people blame on those evil expander balls really comes from neck walls that are not even around their circumference.

I've demonstrated this with a plain vanilla RCBS FL sizer I use a lot for loading 308 ammunition. If I size a piece of brass with no expander ball and check it the neck runout is basically surface noise from the brass moving under the tip of the dial indicator. If I put the expander ball in place, unscrewed a half turn from locked down, and size a piece of good brass the runout on the neck will usually show a thousanth or less and always less than two thousanths. Doing the same with a piece of brass with a bad neck will make the runout go wild.

Your seating die will have an easier time putting them in straight when the brass is even and sized straight too.

mathman

Any measurement using a pilot and checking the outside variance will NOT give you true readings of variances. The inside of neck walls can have depressions so that the neck wall doesn't contact the pilot therefore giving a false reading. Measuring the neck walls with a ball micrometer in several places will give a truer reading. Even then you must measure in multiple locations on each neck and there is still the possibility of missing some of the extremes. Tools with the pilots are a start but they aren't accurate.

bobski, what about using resized brass? Won't the fireformed case be relieved of depressions/dents?

I use the Redding tool on resized brass.

If one trims for length and simply looks at neck thickness the evidence is typically obvious to the naked eye. Tossing rejects is simply a waste of otherwise fine cartridges. Likely, you will find the variation you are looking for, and as a cure I suggest using a tool that simultaneously reams and turns the neck. Passing the neck wall between a reamer and cutter will generate a more consistent product than tools that simply work one surface or the other. The process halved groups sizes for a 7 mm Mag and 22-250, so now I simply turn necks on everything I own.

1mimute, I am hoping for a low cull count. Down the road, I may ream/turn, but I am just a hunter that likes reloading. The thing that has made me decide to check for concentricity and now measure necks is this. I freaking hate it when I am trying to find a new load, and get unexplained flyers. I am hoping to eliminate that.

This is from Mule Deer. Not saying what ever he writes is the gospel, but he has more resources than I do to check such things.

Over the years much advice about "uniforming" cases has been printed. I've tried it all, from reaming primer pockets to weighing cases to removing the little burr on the inside of the flash-hole. All these details may have some slight effect on benchrest ammo, fired in rifles capable of one-hole groups, but even some benchrest boys have given up on most of 'em.

Why? They don't make any difference. The only case dimension that seems to help shrink groups is uniform neck thickness. Ideally, necks shouldn't vary more than .001" in thickness. Before measuring, most bulk brass must be run over an expander ball to remove dents. Otherwise you'll be measuring dents, not brass.

All of this takes time, but you only have to do it once. I buy most of my brass from Midway USA (5875 Van Horn Tavern Road, Columbia, MO 65203) in 100-500 round lots, and sort necks on any batch from Remington or Winchester. The reject rate usually runs between 5-20%, and you can use the rejects for offhand practice or dummy rounds--or neck-turn them to the same uniformity as the "good" cases.

I used to turn necks, but no more. As a general rule brass with bad necks is lopsided all the way down through the body. It may be straight after it's fired, but won't be after full-length sizing.

I don't bother weighing brass anymore, either. Most of it's just too uniform these days. The first time I've weighed brass in a couple years was yesterday, just for this article. The only batch that varied more than 2% was some Winchester .300 Savage brass, at 4.8% still only plus or minus 2.4%, which matters not at all in the real world. I use the same brass for handloads in both of my Savage 99's, one peep-sighted, the other scoped. The peep-sighted rifle (a takedown) will average a little over 1" for 3 shots at 100 yards, the scoped rifle under .75".

Nope, all it does is "transfer" the depressions to the inside. When you pull an expander through, that transfers them again to the outside.

All this is a tempest in a teapot. Generally it doesn't matter that much in big game rifles anyway unless you're way off in extremes. The .001" variance is a good general rule. I've never been able to see any difference in those with a bit more variance and I use .0015" as my breaking point. I'm unsure what even .002" has shown in accuracy. Even with minimal variance, most hunting rifles won't show enough difference in group size to really tell much of anything, it's just a matter of where you want to draw the line. You still have variances from case to case in the elasticity of necks. As long as you are concentric and your wall variances aren't extreme enough to vary group size out of a hunting rifle, it doesn't matter much.

This is the type of tool you want for proper readings on neck wall thickness. LINK

Very good advice.

Hey Sakoluvr

I measure neck thickness 2 ways. The easiest way is with a Casemaster or similar gauge



Note the mark on the collet that comes down onto the neck. The trick for me is to lift the collet, rotate the case and bring the collet back down. If you try and roll the case to get a continuous reading it is hard to get a consistant measurement because of the difficulty holding the case level.

I also have a ball micrometer



which is more accurate but much harder to use because it is awkward in the hand. With the ball micrometer you will soon discover that the thickness also varies with distance from the shoulder.

Sorting by neck thickness would seem like an exercise in frustration to me because of the many differences in neck thickness depending upon where on the neck the measurement is taken. For instance with most Remington brass the neck thickness varies .002" or more on every case, if you find a case that seems consistant just keep measuring in different places and you will find a significant variance, so how do you sort it? Nosler brass is better and so is WW brass, IME, your results might vary.

I usually neck turn new brass after neck sizing with a Lee Collet. The Forster turner I use then fits very tight in the neck and depending upon the original thickness I will turn then entire neck




especially in a tight necked gun. Or I will do a partial turn (no good pic) where I turn 75% of the neck so all of the neck is within .0005" of the same thickness.

I am not at all sure how a variance in case body brass thickness would transfer to the neck brass again or how it would affect case concentricity. Possible the case expansion characteristics would vary, but how much and if you PFLR with shoulder contact then what would it matter?

But to answer your question, I can measure the relative neck thickness of brass much much quicker with the Casemaster. It also has the advantage of being useful in other ways also.

Woods, Welcome to the campfire. Great illustrations. Thanks, and I hope you post often here.

When reaming and neck turning in one pass, how is the "depth of the cut" adjusted?

With factory chambers, does neck turning/reaming make sense? Can concentricity be improved by neck turning or reaming or both.

Nope, not in my opinion. Brass is too cheap to mess with a lot that has extreme variance. Much brass is available from all our domestic manufacturers whose neck wall variance is acceptable as is.



Yes. If the brass is way off, skews the bullet when seated, or otherwise affects concentricity, obviously uniforming the walls will help. Reamers that are free floating such as those by Forster, can cause more problems than they solve. Unless used in a reamer die, the reamer will follow the path of least resistance when put thru a neck. The hole it reams can be stovepiped, at an angle to the concentric axis of the case, making the problem worse than when you started.

I don't ream and neck turn in one pass. The K & M turner does have a cutting mandrel with a cutter on the end that is made primarily for do-nuts, http://precisionreloading.com/KMProducts.htm



"K & M has specially designed a new carbide mandrel that has four flutes for removing the "dough-nut" that is located at the neck-shoulder junction of a case. Removing this extra material aids in a consistent high volume flow of powder gas. A small difference in the shape and diameter of the hole makes a huge difference in performance. This new carbide mandrel will also cut the extra material out of this area if you have changed the neck to a different caliber. This mandrel works while you neck turn, so you will not have to perform a separate operation."

It doesn't really "ream" out the neck like a regular reamer, http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=590193&t=11082005



that attaches to a trimmer. I don't know of any equipment that both inside reams and outside neck turns at the same time. Anyway, I don't ream so perhaps someone else can help you with that.

With outside neck turning the depth of cut is adjusted on my Forster turner by loosening the lock on the cutter blade and turning the dial to move it in or out



There is a little trial and error to get it just right and you do need a good way to measure neck thickness.

IMO, neck turning does make sense, even in factory chambers. It helps to make your bullet release a little more consistant. It will reduce runout just by physically removing the high spots on your brass neck but also by making the neck expansion more consistant. Of course, this is my opinion and largely unproveable and others opinions might vary.

I do know that outside neck turning with my Forster hand held is one of the less odious tasks, only has to be done once and doesn't take that long. I would recommend the Forster turner over the K & M, even though the K & M has the cutting mandrel because the Forster turner has a wide blade that makes for a smooth cut



which I do not think the K & M has since I have heard others complain about the circular grooving with the K & M. Also, the hand turners are the way to go. I originally used a Lyman turner on a hand crank type of trimmer and it did not do a good job.

bobski, thanks. I value you your opinion, and many opinions are more data for me.

woods, why turn all the way into the shoulder? It looks like you went a little past the neck/shoulder juncture.

If you remove brass from the entire neck (all the way around), does that mean you are cutting too deep b/c only part of the neck wall is thicker in an area or two? Or do you just bring it all down to a "uniform thickness?

I love pictures.

I have the K&M. I did get some grooving initially, but now I just "feed" the case in slower and voila! no grooves. I use a small cordless drill to turn the cases - the hand tool took way to long - so it spins fairly fast. The other advantage of the K&M - you can put a dial indicator in the end opposite the cutter and measure neck thickness as you go - this alone makes the K&M much better in my opinion. I'll post a pic later.

Woods:
"I don't know of any equipment that both inside reams and outside neck turns at the same time."

RCBS makes a cutting/reaming tool. It is not something I would use in a commercial setting, but it works for me. Setup is a little tedious, but then again, anytime one is striving for precise dimensions some set up is always involved. I use one and simply use feeler guages to set the reamer/cutter span. Given that most brass only receives a single treatment, it's not such a tedious task.

Edited in: Here's a link.

Link to RCBS reamer/cutter

I get measurable improvement in run out and suspect that neck tension and release of the bullet are more consistent too. My practice is to fire form, neck size, length trim, anneal, then neck turn/ream.

I do not have any custom chambers, but experienced almost a halving of group size with my long possessed 22-250 and 7 mm Rem Mag. Both of those were running Remington brass that had several firings, and the issue was visibly obvious by looking at necks after length triming (thick/thin sides). Both units had shot well, but I would get those frustrating 1 out 5 or 6 fliers before I started turning. That's not the case anymore, and they both stack them in there. Since then I've not done any before/after comparisons, as all cartridges/calibers are exposed to the same treatment as standard operating procedure.

If I indeed owned some tight necked units I would probably ream/turn to a new surface through out. I select a thickness based on published cartridge dimensions (thickness = (cartridge outside neck diameter minus caliber)X 0.5), and my cuts usually expose about 65 to 75% new surface on the outsides of necks. That being, I'm likely a thousandths or so short of perfection.

The process may not help in some instances, but quite likely, it certainly won't hurt anything either. 1Minute

1minute- if the neck diameter of a .308 is .343, then .343-.308= .035 x 1/2= .018 So is that how much you set the cutter in to remove that much brass? You use feeler gages to adjust that?

.343" is a fired neck or chamber diameter. You need to use the neck diameter of a loaded round, typically between .331" to .338" depending on brass.

Some LC stuff I recently measured had .014" neck walls.

whoops, thanks m

Yes, that's the math process although 0.018 sounds a little thick from memory. I don't own a 308, so can't comment on the specific values. With a tight throat unit one would go to the dimension needed to chamber a loaded round without pinching the neck. My feeler guage set has all possible combinations of material (like 2, 3, 4, 5, 6, 7, 8 thousandths etc), so they can be stacked together for any desired span.

Being away from my notes right now, values between 0,012 and 0.014 come to mind for the calibers I own.

Yep, .0130 or .0140. I originally used the fired case dimension as mathman pointed out. Does the little micrometer wheel give an accurate reading when zeroed, or are feeler gauges a necessity to double check?
Is the cut surface uniform, or are areas "skipped" where the brass is not thicker?

Sorry about all the questions folks. I like learning new areas of reloading.

Hey Sakoluvr

Turning a little into the shoulder is supposed to mitigate the development of do-nuts. Here is a link to more than you will ever need to know about do-nuts http://home.comcast.net/~jesse99/doughnuts.html

You have to evaluate your situation to determine whether you want to turn material off all the way around or just hit the high spots. With the measurement you gave of .343" for a 308 caliber chamber, I would do the math like this

.343"-.003"(minimum clearance around neck)=.340"-.308"=.032"/2=.016"

What that means is that you do not want brass any thicker than .016" on either side so that you have at least .003" clearance around the neck brass. So if you happened to buy some RWS brass that was extra thick and varied from .017" to .019" then you would have to turn. If you have some WW brass that varied from .014" to .015" then turning is not required and you can choose not to turn or clean them up to a consistant .014".

The opposite kind of scenario is like in my 6.5 rem mag with a Douglas barrel that the smith chambered with a .292" neck, the math would be

.292"-.003"=.289"-.264"=.025"/2=.0125"

The only kind of brass that I can buy is Remington and it varies from .015" to .017" and I have to turn that all down to .0125". Now that is some serious hand cranking and I usually do it in 2 steps because the cutter binds when you try to bite too much off at one time.

Most turning will land somewhere in the middle of those 2 situations but it depends upon your chamber and the batch of brass you have. My Hart barreled 280AI has a .313" neck and the Nosler brass I use is a very consistant .013" to .014" and that works out to be just about what you want to turn for a custom neck.

1minute, which one of those tools turns necks and reams necks at the same time? I don't think it is the 3 way cutter



or the pilot reamers.

Sorry, no pics this time, but BTW, isn't the 6.5 rem mag the original short magnum?

woods- sent you a PM.

Woods:

Lets try this Midway link. The photo does not show a reamer installed. Sorry about the first pass. 1Minute

Midway link for reamer cutter

Went back in my records - grooves disappeared when I started using the cordless drill to turn the case - like I said, just feed it slowly into the cutter. You cannot feel any grooves whatsoever!

I;ve come to the conclusion that this is like everything else - it's nice to have choices, and some will like these and some will like those . . .

Here are the pic's:

K&M Tool w/ dial indicator attached - makes it very easy to adjust, and you can measure neck thickness alone without a separate tool. Alsl notice the adjustment on the end of the pilot - excellent for controlling the depth of cut into the shoulder.


Here's a piece of 338WM brass that was recently turned - barely into the shoulder and no grooves.


This is the adjust for the cutter - note the threads inside. The cutter itself threads (via reverse thread) into the adjustment screw. One full turn is only about 0.0025" if I remember right - very good for fine adjustment of cutting depth.

Here's a link to an excellent case prep procedure (maybe a bit overboard for our hunting rifles, but still an excellent read):

Case prep procedure

Thanks 1minute

I see how it works now, like a hand cranked turner with a reamer for a mandrel. Reading the last 2 product reviews would make me hesitate to purchase one though although I like to reserve judgement until I try things myself. It makes sense to me that if you have neck sized to uniform the inside of the neck which pushes all the variations to the outside of the case, then outside neck turning would be sufficient.

Hey TXRam (do you shoot at American Shooting Centers?)

I am not badmouthing the K & M neck turner at all. It is capable of doing a couple of things that the Forster is not, like the cutting mandrel, the pilot depth adjuster and the dial gauge. It is an excellent instrument and I have experimented with one at a friend's house when he got his. Sometimes I wish I had sprung for the K & M but most of the time I love the wide blade and simplicity of the Forster. The cutting mandrel will scar up the inside of the neck unless you get the expanding mandrels also. Add in the cost of the individual cutting mandrels and it can cost much more to do about the same thing.

I've seen that article before and that is where the idea of turning a little into the shoulder came from. On the Forster turner instructions if says in bold not to turn into the shoulder. I alleviate the do-nut problem by sizing with a washer on top of the shell holder anyway



and leaving the shoulder/neck junction chamber size



but that is another whole separate discussion.

woods, I totally agree with your points - that's why I said that it's nice to have choices, and be able to pick the tool/rifle/caliber/cartridge/... that's best for each of us. I don't use the cutting mandrels - like you, I feel outside neck turning is all that is needed if you expand the neck to uniform the inside, which I do with the K&M expanders.

I have never shot at American Shooting Centers, but I would like to - have had a hankering to do some longer distance shooting than is available at my range (PSC - Pearland Shooting Club).

I use the Redding Competition dies, and I do not size the neck all the way to the shoulder - same principle as your technique with the washer.

Woods:
"It makes sense to me that if you have neck sized to uniform the inside of the neck which pushes all the variations to the outside of the case, then outside neck turning would be sufficient."

I think I know what you thought you meant, but I'm not sure you said what I think you thought. But then again, maybe you did.

We are likely discussing the effects of a flea on an elephant's ass here. Given that metal can both flex and spring to some degree, I don't think that neck sizing or expanding literally pushes all surface variation or imperfections to one surface or another. Reaming or cutting independently will allow some flex of that imperfect surface away from ones cutter. When the material is simultaneously passed between 2 cutting surfaces, however, that potential flexing escape route is eliminated.

My issue with the hand cutters is that I doubt that I can hold my cartridges perfectly square with my cutting implement. I know a mandral helps, but it is only grasped by a short section of neck and one may still induce some out of line flex.

The rotary reamer/cutter implements have their issues too, as there is typically some play in the implements we mount our tools on. If we all had 5 hp mega dollar lathes, we could eliminate that issue. I think the biggest criticism of the RCBS implement is setup difficulty. That could probably be eliminated with some design changes and development of a $400 reamer/cutter and more secure cartridge holder. I probably wouldn't buy one though until I took on the benchrest circut.

It's been fun. Shoot fast and straight. 1Minute

Hey, let's talk about do-nuts. Are they inevitable if you turn brass? 1minute, I want to just remove what needs to be romoved on a lop-sided neck. Do you find that the cutter "skips" the thinner sides and cuts the thicker sides? Looking to improve concentricity and create even neck tension.

Almost. Should you ever full size, or partially full size, the brass is squeezed forward. The thicker unturned part of the shoulder at the junction becomes the donut when this occurs. In benchrest where the cases are mated to the chamber from the gitgo and never full sized, they are avoidable.


Yes, with reasonable brass where you clean up about the recommended 75% the variance will be way down.

bobski, so that is the reason to keep that juncture thinned.

Wondering- you just need to turn necks 1x out of the gate, then go ahead and get into the shoulder a RCH, so when/if brass flows forward with resizing, that spot will be thin and and the do-nut will not form. Right?

Right. Problem is you have no clue how much to go into the shoulder, it's just a guess; too far and you WILL separate and leave neck in chamber and likely at the most inopportune time, like that second shot at game. Also, if there is quite a bit of variance in the necks you know for sure that variance will be at least the same and probably more in the shoulder and body and when you get a donut it will NOT be uniform; one side will always be thicker than the other and will skew bullets if they are seated below that.

For the record, I see far more disadvantage to turning necks than advantages. As a matter of fact my experience indicated that there was actually a loss of accuracy and except for the couple of tight necked BR rifles I've had, I avoid turning preferring to buy brass that has less than .0015" variance and using it; less problems and a lot less work, but then I HATE to turn necks anyway. I have the Sinclair turner, mandrels and expanders. Sometimes for real expensive brass, or wildcats, you have few alternatives. One alternative is a reamer die which is what I use to make 338 Jamison cases out of 404 Jeffery or 338 RUM. Particularly the Jeffery cases are over $2 each. You'll get a donut in those eventually and at that price it's worth the effort to salvage them and extend their life as far as possible.

Whew, lots of data points to ponder. I don't want to open up a can of worms. I really have the wrong personality to be reloading. Things are never good "enough".

I find that my run of the mill brass is imperfect enough that there are usually some exterior cutting skips. If one was rich enough and could handle the cost of rejects, he could probably assemble a batch that did not exhibit such patterns and were therefore closer to perfection. I have one set that way for only one rifle, a 22-250, where my initial brass collection totaled about 600 rds. That batch had primer pockets worked up, were fired, trimmed, reamed/turned, and weighed. I took the 100 closest to average weight and sorted them from lightest to heaviest, etched on a number, put them in order in my ammo box. Any increase in pressure, if there is any, will be moving consistently and only slightly upward as I progress through that batch. Talk about anal? Can't afford to do that with my other units.

As to doughnuts: I would assume that if we full length resized and did indeed move our imperfections to the interior, running the reamer well into the cartridge would remove the doughnut.

I think the issue with doughnuts is 1)an inconsistent grasping of the bullet, and 2)perhaps some disruption of gas flow.

I neck size only, and do run my reamer deep. My thoughts are that the fired cartridges fit into my chamber and that if there is doughnut on the exterior surface, it would be due to a faulty chamber. If it remained on the exterior in that instance, it would be a non issue.

I tend to use mid weight slugs, and with the exception of my Weatherby's, try to get near the lands. That being I don't think I would ever have a doughnut grasping a bullet. Most bases don't make it down through the full length of the neck. Disrupted gas flow maybe.

Have good one, 1Minute

I know I have experienced this, and don't folks do this to have concentric support in the chamber neck area: only resize the neck about 80% down. After slipping only part of the neck in the bushing, a doughnut appears where the brass did not enter. It disseapears after firing. Is that the same flavor of doughnut as a neck turned doughnut?

No, the dreaded donut is where a ring of thicker brass migrates upward from the body/shoulder of the case into the neck wall.

Ahhh, different flavor. Thanks mathman.

Only problem with that is that the donut will NOT be concentric. The high spot will cause the floating reamer to "float" to the path of least resistance. The back side of the reamer can then stovepipe the interior of the neck and permanently skew the bore of the neck making the whole effort a waste of time.


Grip on the bullet will force the donut to the exterior. Grip would probably be the same. Even if it weren't, how much difference will there be from extra pressure and grip on one side from only a small fraction more contact and how much does that affect grip, pressure and accuracy? Not much in my opinion. I therefore respectfully disagree with that concept.


How can a brass problem, a donut, be due to a faulty chamber? And if an uneven protrusion forced to the outside of the brass on bullet seating skewed the cartridge in the chamber, it would cause a non-concentric seating of the cartridge in the chamber.

Again, if the donut is uneven as it is almost sure to be, the reamer will take the path of least resistance and possibly stovepipe the bore of the neck.

Mathman: Yes, that has been the explanation I've most often seen. Flow from the shoulder to the neck shoulder junction.

In a factory chamber where there is significant clearance around the neck, wouldn't the following sketch apply



where the sizing of the neck would negate the contact of the do-nut on the bullet?

Do-nuts have only been detectable to me when I have a tight neck chamber with .003" clearance so that a fired case inside neck diameter is already tight on the bullet. Then you can slide the bullet in and it will stop at the do-nut. But on a factory chamber with lots of clearance it is impossible to detect, unless some of you have found a way. The do-nut must still be there but the added clearance would make the inside neck diameter large enough for the bullet to slide past it. In that case it wouldn't matter anyway cause it will never contact the bullet, unless sizing the neck smaller sizes the do-nut down also.

Make sense?

Bobski: Yes! I'd agree the conventional donut is typically not a chamber issue. It's brass flow from the shoulder to the neck / shoulder junction with repeated firings and it's an inside the cartridge problem.

As to "floating" reamers.... Yes! I again agree that one will always have issues with such a system looking for the path of least resistence. I for one would not use such a tool.

Regarding faulty chambers, reamers wear out, wear inconsistently, and experience all kinds of abuse and damage. If any event is even remotely possible, it can and likely has happened. If indeed such an issue did arise, it could be partially treated by indexing ones cartridges to make sure they were all consistently oriented in ones chamber. There may still be a bullet flight issue, but if it has the same effect from shot to shot, we can perhaps live with it. Some bench folks do go this route just to cover their butt. They may have an unrealized problem, or they may not. Either way, a consistent approach always helps.

The point that I perhaps did not clearly make, was that the typical donut fix should be addressed from inside the cartridge as opposed to routinely cutting into the exterior of ones neck/shoulder junction for a problem that might not even be be there yet.

Varying neck wall thickness within in a single cartridge will certainly affect bullet/bore alignment if the high side has enough dimension to touch the chamber neck. Secondly a thicker side will exhibit less flex in the sizing/seating operations and induce bullet runout. Both of those are bad things for one seeking perfection. I try to keep my bullets seated within the area of a cartridge neck that has been both reamed and turned. That portion of the cartridge is a least as consistent as I can make it. Any portion of a donut that is not removed by the reamer though, can still have some influence on gas flow. That, I will just have to live with.

Lastly an inconsistent amount of grip on ones bullets as we progress through a series of cartridges will mean more or less pressure is needed to initiate bullet travel. That variation will also help open up ones group. In this instance, chaos theory may apply in that very subtle differences at the beginning of an event, can have substantial impact on the final outcome. Have a good one, 1Minute

Woods: I'd agree that donuts are less of a problem in a loose factory chamber. In many instances, the tighter we make our tolerances, the quicker things can go to hell.

Sort of like a sloppy AK47 that can come out a wet sand bucket and keep firing. A precision American made semiauto, however, will quit nearly every time.

If both are kept spic and span though, our unit is the more accurate of the two.

I think we agree, especially on the issue of the donut.

Our only issue is the impact of the varying contact and "grip" on bullets and how much a group is thereby affected. I question there is "substantial" impact; I think it is minimal on group size, especially if necks are regularly and consistently annealed. Cheers.

Good illustration Woods. Makes sense except for the fact that donuts are not necessarily "small" and if flat base bullets are seated into the shoulder area they WILL cant the bullet. Usually boat tail bullets don't quite get to that point, but they can as well depending on chamber configuration.

Guess I've had my share of donuts, especially in cases for wildcats where the thick body of a parent case becomes the neck for the new case. The very thick body brass is left in the shoulder of the new case and eventually becomes a very intrusive donut.

While out for a drive last evening I came us with the concept for the ultimate magnum spiffy super excellent competition grade neck reaming system that might even do away with the need for turning. One would deprime his cartridges with a universial deprimer, run a cartridge into a neck sizing die, and then ream while the cartridge was still fully within the die. That would lend near full support to the exterior of the neck. If we did away with the threads in the top of the sizing die, sized the shank of the reamer to precisely fit that hole, the reamer would be extremely well supported and minimize potential wobble or lateral movement. Now to assemble my machine shop. Patent pending. 1Minute

That's what is called a reamer die. I got mine from RCBS years ago and they may no longer be available since they stopped their custom orders but it would be worth a call if you're interested.

The reamer is a close fit in the boss at the top of the die. Works well. I don't have picture but will take one and get it possted in due course.

Tried the RCBS site and there are no pictures available and they only list one. They do have something called a Pilot/neck reamer and only one reamer die listed now at their site: http://shop.rcbs.com/WebConnect/Mai...Type=0&searchDescription=reamer+dies

Maybe C-H or Redding have them. They aren't cheap.

Here's photos of reamer die. This one is a FL die on left for comparison, reamer die and reamer on right of it.



Reamer die with reamer in boss as when reaming inside of neck. Incidentally, the teflon block in the background used for support, is drilled in various calibers. That's what I use to "straighten" eccentric necks when checking and verifying concentricity of reloads.



The tolerances are pretty tight between reamer and boss. I've never measured the movement of the reamer end but it's minimal. Another shot of reamer and die.

Sweet! Will have to look into it.

Lee mad something similiar many years ago. They still might make them.

I have one, in .30-06, that I purchased about 25 years ago. They are designed to work without neck expanding. The case is pressed into the die, then the reamer goes in through the top of the die, which aligns the cutter, then the cutter reams the case so that the inside neck diameter is about .001 smaller than the bullet.

The bullet is held in place by the tension of the bullet expanding the neck .001".

It works, or at least it reams the neck, but I have never tested one of the loaded rounds for run out. I have also never measured the neck wall thickness to determine if the reamer centers the hole in the neck.

25 or 30 years ago, I didn't even know about uneven neck wall thickness or concentric ammunition.

Reaming dies seem to be a thing of the past, at least in a preliminary search I haven't found any on the Lee, RCBS, Redding or Forster websites.

But, with the Forster reamer http://www.forsterproducts.com/store/detail.aspx?ID=13



which has the following description:

"Thick case necks can cause high chamber pressures and flyers. The Forster Neck Reamer mounts in the cutter of a Forster Case Trimmer in place of the pilot and removes the excess brass from the neck walls. The Forster Neck Reamer is manufactured from high grade, wear-resistant tool steel and ground .0025" to .003" over the maximum bullet diameter. The staggered tooth design cuts the brass smoothly without chattering. Photo illustrates three different sizes. Choose size from reamer number list below.
$24.00"

you could ream out the neck .003" larger than bullet diameter and get rid of a do-nut that way.

For example I have a 6.5 rem mag with a .292" neck size. Doing the math .292"-.003"=.289"-.264"=.025"/2=.0125" for neck thickness. Then after I fire the case the reamer should just fit inside and not take any or very little off the inside of the neck brass until it gets to the do-nut. Then, bye-bye do-nut.

The questions would be:

Will the reamer follow the channel of the inside neck and not stray off to one side?

Would the reamer fit in my hand turner or would I have to buy a Forster hand crank trimmer?

Also, when you fire a case the brass forms to the chamber and the outside of the neck is smooth and concentric. It is after sizing that the imperfections get moved to the outside of the case. Theoretically you have gotten rid of the variations in neck thickness by outside neck turning already, but would whatever are left of the variations in neck thickness cause a problem with the reamer as far as getting off center and taking brass off where you don't want to?

Anybody doing this?

I think I've tried every which way to get rid of donuts. In tight necked BR cases I always used to end up throwing them away and starting over. About the time I gave up BR there was a tool, a reamer of sorts, that became available to clean the donut out from the inside. Forgot who made it and don't know if it was successful as that was about the only thing I didn't try. It had the facility by its design (something like a hook on the end of the reamer,) to get the donut and a bit of the shoulder from the inside.

The reamer will always find the path of least resistance unless the brass and reamer are both held rigidly and backed up. The offset can be minimal or significant, depending on the imperfections of the brass.

Reaming with the Forsters, of which I have many, some of which are "custom", you could never completely do away with the donut on its high side. There's almost always a high side. The brass springs out when you ream, then springs back. You were successful sometimes if the high side was minimal, and many times not.



The Forsters don't handle well in any hand turner. Mine are round with a single small flat on one side of the end. They are made to be used in their trimmer where you can get enough pressure on the allen screw to hold them when they start cutting. In a hand held there is no simple way to hold them from spinning when you start the cut.



Yes, it's those imperfections of which we speak; the reamer will follow the path of least resistance.

I've tried turning the outside after expanding the necks and donut after FL sizing (thereby moving the donut to the outside,) and again the brass springback still leaves vestiges of the donut somewhere. If you don't turn the outside you then have a neck with uneven thickness at the base of the neck. In hunting rifles with .002" clearance on the neck all the way around it might not make much difference. Where you truly notice this is on the non big game rifles. You can usually figure out something on rifles with relatively loose dimensions in the chamber but if we're talking "perfection" and trying to shave tenths on your groups, I'd like to find a way. I think I've tried everything, except that gizmo mentioned above, and I never have. Lord knows I've tried.

Thanks bobski

The Forster hand held neck turning mandrel has a flat spot on it also where you set a screw to hold it in place



I have 3 guns with tight necks, the 6.5 rem mag (.292", a 280AI (.313") and a 338RUM (at least I hope it will be tight at .367", I'm waiting on it now). I think I will give one a try. If everything could be set just right it could do a good job not only on the do-nuts but also as a fine tuning of neck thickness.

I think I know what you're thinking as far as fine tuning neck wall thickness. Try it but I think you'll be disappointed. You'll quickly see the the necks don't all spring back from either firing or reaming quite the same amount and you'll end up with varying neck wall thickness.

Let me throw in my .005 cents worth on neck measuring turning.
I modified my RCBS Casemaster to accept RCBS flash hole pilots for measuring neck wall thickness. I found the factory set-up too slow and too susceptible to error for me.

If I do decide to turn necks--which is rare for me with hunting rifles--I run each case over a Sinclair expander mandrel first. this transfers all the irregularities to the outside of the case to be turned off. I then turn the minimum amount of brass off the get the necks to .001" or less variation in neck wall thickness.

I use a Sinclair neck turner NT 3000 and turn down as far as the cutter will cut. I have never had a donut problem.

I also use an expander ball when sizing as much as I can. I think this is especially important with unturned necks as it keeps all the irregularities n the outside of the case neck where they won't affect bulelt seating and bullet pull.

Blaine, quit making things so simple.

I decided to turn necks, just to see how it all works, and learn and try something new. I opened up the necks first with a button, then used a Redding case neck gauge to sort the brass.

I sorted brass, and separated out everything >.0015". I took those (~15% of this lot), and made my cutter adjustment on them. I turned until I got at least a RCH <.001".

I am thinking that now I can turn the rest of the cases in that lot with the same cutter depth.

BTW, this is for hunting rifles.

My RP .308 brass gave me ~18% > .0015".
My RP 7-08 brass was <10%.

Mathman,

Before measuring runout, did you first measure neckwall thickness to determine "good" vs "bad" brass?


Casey

Donut update

I have a Hart barrel 280AI with a .313" neck, I turn necks to .0125" so the math is .284"+.0125"+.0125"=.309" which should leave .004" clearance.

Well, I definitely have a donut. This shows how far the bullet will go into a fired unsized case


So I sent off for a Forster reamer not knowing if I would need a hand crank trimmer or if I could use it in my Forster hand turner. It came in and, thank you Forster for being a fine company, the reamer and the hand turner mandrel are the same size


The case before I started measured .0125" neck thickness


and looked like this inside (you can't see the do-nut)


Then I locked the reamer in the turner and adjusted the blade


to ream the inside and turn the outside (just a touch up since these had been turned when new) at the same time


The reamer took a little off the inside and followed the neck without a wobble and the donut was gone-gone, bye-bye
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0717.jpg[/img]

The case was reduced in thickness .0005"
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0718.jpg[/img]

The inside of the case was a little rough
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0721.jpg[/img]

So I chucked it in my Zip Trim and steel wooled it
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0719.jpg[/img]

and it came out smooth and shiny (well at least smoother and shinier)
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0720.jpg[/img]

So I have come to the following conclusions:

1. If you have a factory chamber and substantial neck clearance then you probably won't have a problem with do-nuts even if you have them
2. If you have a tight necked chamber you can turn your necks for .003" or .004" clearance and get rid of the do-nut with the Forster reamer

BTW, in answer to your first question about what to measure the case necks with, I just recently got a Holland's micrometer holder and it is like having a third hand
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0727.jpg[/img]

Big difference, I'm as happy as a gopher in soft dirt! Plan to try 5 identical loads with the do-nut and without the do-nut to see if I want to get rid of them or not.

woods, once again thanks for your great illustrations, and taking the time to share them. What brand mic is that?

It is a Frankford Arsenal http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=257288 . I have had trouble with Frankford Arsenal stuff before but this micrometer seems to be doing fine.

and the holder is a Hollands http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=798812

Hey woods, you're a helluva salesman! I'm going to buy that stand; the Starret runs much more than that and it looks like it will do the job, thanks. Bet you could convince someone to go into a cave after a bear!

I too have managed to get rid of some small donuts with a floating reamer. If you go in slowly and not cut too agressively, and if the donut isn't too much larger on one side, you can. However, I'll repeat, the reamer in addition to cutting also slightly expands the brass so that when you are done there is a bit of springback. Where the donut is located you can't quite reach with the tube micrometer but if you split a case and measure from the side you will note a difference measured in the .0000".

bobski, you must be as much a discerning guy as I am a salesman!!

See this bear


this was in Colorado and we did track this wounded bear to it's hole under a rock as big as a house and I did talk the smaller buddy on the left into that hole after that bear! I told him I would gut it if he went in and got it. We heard it die or at least I was 90% sure it died. He did complain a little about the spiders and big claws staring him in the face when he was far enough in the hole for me to just be able to see the soles of his boots. Of course it was hard for me to hear him complaining much cause I was laughing so hard!

Hey, wait a minute, you don't know a guy named Hot Core do you?

Back to the subject, you don't think that having a outside turning blade on the outside and a reamer blade on the inside will negate the effects of springback?

I'll be damned! From my past training I learned to be a good judge of character and I thought I was. I had NO idea this might have been the case! Neat story and good pics. Are you the guy on the right? You ARE one helluva salesman. Remind me never to go hunting with you!

What kind of name is Hot Core? The closest to such a name I've come is the Hogg sisters in Houston, Texas. He was an old oilman and may have been involved in the beginning of Humble Oil, later to be Exxon. He named his daughers Ima and Ura. Ura died before I moved to Houston but Ima was then an old lady that was quite a philantropist; very well known in Houston in the 50's and 60's. I can't imagine Mr. Core naming his son "Hot". Are you joking or does he have something to do with Speer bullets?

Yeah, if you can work both sides concurrently that would take care of the problem. I never figured that part out except for that old tool I mentioned earlier. Reason I know of the springback is that after using the floating reamer I've tried expanding then turning the outside. The cutter never touched the upper part of the neck but when I got to the base, the site of the donut, the cutter started taking off brass, and on one side more than the other. That's when I split a case, measured, and sure enough there was a slight disparity, don't recall the exact .0000". That's when I went to the reamer die and that took care of the problem. I'm sure your way would also do it. But then it really doesn't matter much if the bearing surface of the bullet never reaches the donut when seating it. In my case I was working with a short action that required all but the lightest bullets or boattails to seat at or below the donut to fit the cartridge in the magazine.

Hot Core, The last word in reload methods and tooling...
Very knowegable but ................

Woods has already cost me $$$.$$

Remind me to tell of the time when I talked another buddy into catching this rattlesnake alive so we didn't booger up his head with birdshot



I had him put it in a 5 gallon bucket so I could shoot it once right in the top of the head with a pellet gun. I talked him into it by telling him I would pay for the skin mount and we would trade off putting it on our walls. The ungrateful bastard came by the other day and saw it after 12 years, remembered the deal and wanted it back!



Seems there would be no springback issue if the brass were being cut from both sides concurrently. Where would it spring to?



I guess he doesn't fight his pressure wars and bad mouth Stoney Point "thingy's" over here, does he?



Can I interest you in timeshare on a 6' rattlesnake skin mount? Maybe we could change that $$$.$$ to $,$$$.$$.

Looks like removing the do-nut has a positive influence on accuracy