Concentric ammo

[Digital Dan]

I'm curious about what your thoughts and more importantly, your methodology for minimizing run out in hand loads. What are your standards of success?

I've seen oft repeated reference to this in many threads here, but not a lot of commentary about "how".

My personal observations are that each gun is its own beast and has different levels of tolerance. I've seldom seen factory ammo that was consistently assembled within a narrow range of concentric measure of the bullet. I think the set up and method of use of the sizing die is a significant part of addressing the matter. Some dies are very good at minimizing run out, some induce it profoundly. I don't believe neck turning has much of anything to do with curing wide variances of run out.

I think straight wall cases are sent from heaven and bottle neck cases more often than not sucketh the swamp water, though they can be healed.

Fire away.......

[s mac]

Good question, I have wondered this myself.

[Love Life]

For me, it depends on the rifle.


For my off the rack guns I do standard load development and call it a day, oh and I sort all my bullets with a comparator.

For my match rifles I practice all sorts of voodoo and hocus pocus. No neck turning, but I do check dies and brass against the concentricity gauge and then check loaded rds. I sort bullets by weight and base to ogive length, minimal shoulder bump, and sort brass by weight and internal case capacity. Even then, I segregate uncalled fliers brass when doing my actual shooting.

I use this tool: http://www.bullettipping.com/products_concentricitygauge.html

I would love to get a Juenke machine some day.

[Love Life]

That should be fun.[smilie=w:

That is full weight as well!! No need to test an empty bra.

[Scharfschuetze]

I don't bother with it for ammo to be used up to 500 yards, but for ammo that's to be used at 600 yards to 1,000 yards in a 40X or with or custom 721 both with tight or minimum 308 Winchester chambers, I'll check for concentricity and make efforts to produce it.

I have a custom made device to check for it, but the RCBS concentricity gauge works well too. I also outside neck turn the high spots off of each case's neck and weigh them too as well as all the other efforts one puts into long range loads.

I also use either the Redding match seating die in a Rock Chucker press or the Wilson "In-Line" seating die with an arbor press. Both will produce "straight" rounds of less than my goal of .003" and usually much less than that. Some cases just don't want to cooperate and they get tossed.

Bullet quality, die quality and design as well as good quality and uniform brass all contribute to straight rounds. Do you need to do it for every day ammo? Absolutely NOT, but for long range ammo I think that it's beneficial. It also gives you confidence in your ammo and that may well be worth the effort by its self when you're hot, tired and thirsty at the end of the day for the long range stage of the match.

[Love Life]

I really like the Vickermann in-line seating dies for bullet seating, but danged if the lee seating dies don't do just as well!!

[WILCO]

To tell the truth, I've never worried about it. My shooting activities are pretty laid back and the small batches of ammo that I produce perform well for my needs.

[Larry Gibson]

Tests of match M852 (7.62 NATO loaded with the 168 Sierra MK) have demonstrated that run out of .004" or less had little effect on accuracy to 600 yards. Like Scharfschuetze I do not bother to check concentricity on my match ammunition to be used to 500 yards. I uniform the necks and use quality seaters that maintain less than .004 concentricity. For my jacketed match loads for use at 600 - 1000+ yards I do check concentricity (I have the same device that Scharfschuetze does) and sort by run out (most often the majority is .000- .015).

With cast rifle loads I do not measure concentricity. For my really accurate loads I visual sort and weight sort the bullets. The cases are match prepped with the necks turned for concentricity, fire formed, minimally neck sized and the cast bullets are loaded with care. Given care in loading they are consistently "concentric" I have found that a proper fit of the cast bullet to the barrel throat is the more important alignment for consistent concentricity.

Larry Gibson

[M-Tecs]

I do basically the same as Scharfschuetze and Larry with one addition. For my 600 yard plus loads neck annealing seems to be the most beneficial thing I do to increase accuracy.

[shooter93]

I don't do much serious bench rest shooting anymore, 99% of my shooting is standing on my hind feet. But when I did I usually found what I hoped was a good load or two then start with the "accuracy enhancing" stuff doing one thing at a time and checking the results. A rail gun could be very enlightening in some aspects.

[country gent]

The first step of true concentric ammo is starting with good cases. I checked neck wall thickness on them and work from there. After you cull a few cases for being out to far section one or two and measure wall thickness close to the head with ball mics. The thickness variation grows as it goes backtowards the head and the brass thickens. Check you brass for run out you cant load concentric ammo on a bannana shaped case either. Straight true cases consistent necks and tension good dies will load more consistently concentric ammo. Another is to seat in 3 steps rotating each step as this helps to center the bullet better. I have been using the redding bushing dies and seater that came with them with very good results for 223 and 308. The other thing to do is sort out 10 perfect rounds and 10 max run out and test in the rifle to see if it knows the diffrence and if so if the group is enough smaller to matter.

[Digital Dan]

Well, thanks for all, here's my .02 on the matter.

Started loading back in 1970 for a RSB and after some years eventually picked up my first CF rifle, a 94 30-30. Then a Hornet, etc, and somewhere along the way turned into a poster boy for the local chapter of Rifle Loonies. It wasn't until around 2000 that I picked up a RCBS concentricity gauge and what I saw caused a quantum shift in loading procedure. I was appalled by the run out on factory ammo. I was not much more impressed by what I was doing either. I add at this point that I do not see harm in evaluating lead bullets with the RCBS tool, the pressure of the ball from the mic is not that great. I have no experience with other systems.

Solutions came slowly. One of the things I figured out with fair alacrity was that straightwall cases don't suffer much in this analysis. One of my ongoing projects at the time was paper patching a .44 mag rifle and after visiting the run out gauge a few times it was obvious there was little to be gained by doing so. My recollection was that run out was typically less than .003" at a point 1/8th" forward of the case mouth. I found the same with a .38 Special and later with the ammo a friend was loading for a .45-70. My assumption at that point and something I still believe is that the geometry of sizing dies for bottle neck cartridges was causing the problems with those cases.

I noticed a couple of things at that point. A case being sized has what is hopefully a concentric die body doing the deed, and was fully supported by that and the shell holder. When withdrawn the expander button was doing its duty with everything unsupported. Again, an assumption on my part, but variations in neck thickness of the brass or flaws in geometry of the shell holder were the only things that struck me as potential culprits.

Then I did a Cerro Safe cast on a RCBS size die for my .30-30. Was not amused to see the body and neck had a different central axis. Did this three times, totally befuddled how such a thing could be and it was not until the third cast was evaluated and the numbers agreed with the first two that I gave up and accepted that somehow, it had been done. Did it matter for the Model 94? No. It shot about 1" groups at 50 yards with most any load and about 2.5" at 100. Did it matter with the T/C Carbine? Yes, quite a bit. I purchased a new set of dies from a different company and a stand alone collet die from Lee. The Model 94 still shot about the same, but the T/C went from loose patterns at 100 yards to sub MOA almost instantly. The original set of dies was inducing run out in the range of .010 to .015", the second set averaged about .005 with no effort at all and much of the ammo hovered in the .002-.003" range.

Well, I began evaluating all my stuff with that tool, amending this or that method, until finally I wound up with what I think was a fair understanding of how to load straight ammo in bottle neck cases using work-a-day dies. I suspect the difference between the press and dies used by the average Joe and the equipment used by BR competitors goes more to producing a lower average range of run out than anything else. Arbor dies? Yep, they work. Can a fellow do some of that with just a neck sizing die? Sure. One of my minor discovery is that letting the size die float a little smooths out a lot of bumps. I do this by use of the Lee lock ring which uses an O-ring to prevent movement. I finger tighten it only. I use Lee lock rings on ALL of my dies for this reason.

Another strategy used by some is removing the decapper and expander ball when full length sizing, decapping done by a universal die for that purpose. After sizing the expander is applied on the down stroke rather than upstroke. It helps enormously if the neck is lubed first. I use powdered graphite mostly, though on occasion I has used powdered moly. With all that said, I have had mixed results at best with this procedure and it is not my go to method of setting that geometry.

Some are of the opinion that outside neck turning is the way to deal with this. Though I will acknowledge that it is helpful, I respectfully disagree with anyone thinking it is the Holy Grail. Basic geometry of chambers cut to SAAMI specs and loaded with ammo meeting the same specs will require there be room for case and neck expansion during the firing sequence. It isn't much, but it is very important in the neck region. Lack of neck release leads to very high pressure excursions 24/7, there is no getting around that. Next time you're playing with your concentricity gauge, run some cases thru it that have been fired but not sized. Check the dimensions of the neck, ID and OD. Check them again after they are sized, note the difference. Most times you will find fired brass remarkably consistent in neck run out. Variations will be very small. Check the same brass after sizing....cry in your beer. In private. What neck turning does more than anything is provide consistency of neck tension, another significant aspect of developing accurate loads.

There was a comment above which I would like to reinforce. The single most productive way I've found to minimize run out is case neck annealing. Softer brass is easier to work and distorts less. Some years back while working loads for a .22 K-Hornet I was having problems with run out and accuracy. I noticed inconsistent effort requirements to seat bullets and annealed the cases. The next batch of reloads of 100 rounds fell into a slot of .000-.002" run out with only two deviants in the crowd. That particular gun was a Ruger #1 and it was remarkably responsive to variations in run out. One of the groups shot with that gun was a string of 22 shots that went .77" at 100 yards. Others, not so much. A Rem 700 in .250-3000 will shoot 1/4 to 1/2" groups with different loads having run out ranging from .001-.005" inclusive to each group and load.

Like I said above, each gun is it's own beast as far as I'm concerned.

Lastly, just an odd observation that related to two Ruger #1s, one the K-Hornet and the other a .257 Roberts. I used to index the case head with a magic marker so that R.O. could be aligned in the same fashion with each shot. I typically loaded the index mark at 12 O'Clock. If I move the mark to 3 O'clock as example, it would displace POA about 90* from the norm, though not necessarily in that direction. They were the only two guns I've shot that did that and the Roberts was much more responsive to such monkey business.

Are there other tricks? Absolutely, but I've ramble far enough here. I think the key to this is understanding to some degree that it is the operator, not the tools that allow one to address this issue. That is my left handed way of saying a bit of thinking can outwit deficiencies in equipment far more effectively than high quality tools can overcome a dull mind.

.02 for free, fire away.

[sthwestvictoria]

Great write up Digital Dan. I like the idea about cerro-safe casting the reloading die! I also find that interesting about the case neck annealling.
I have wondered if part of the Lee Loader producing accurate ammunition (apart from the neck sizing only) was keeping the brass in one orientation for sizing and then seating. The bullet also slides down the straight seating tube and the seating rod also is a lovely tight fit straight down the tube, keeping everything is good alignment.

[44man]

Good stuff. But with bottle neck cases, the size die is the problem. Sizes too much and the expander coming out will bend the neck. Weatherby brass the worst with round shoulders. Lap dies for minimal sizing. Run out is real and I have had 5/16" groups at 100 with my 30-30 by neck turning. Went from over .020" run out to less then .002" by turning. Can't measure on a cast boolit since most are not round so measure case necks.
Yes you can have a chamber out but rare. One piece reamer. Just need straight to bore. Crooked reamer and you lose it. I have found BR practices to be very good with sporters.

[troyboy]

Cocentricty what a can of worms. Well put Digital Dan. If reloading is your game, dont bother. If hand loading is then concentricity is something you have control of. It is about creating a product as close to perfection as possible. Only way for me is to remove variables and this cocentricity is a variable. Relax,lower your seat, unlock the tray table and enjoy the ride.

[Digital Dan]

Can of worms indeed, but I have to view it as an opportunity for interested players to put on their Sherlock hat and ferret out the causes they are dealing with, both with the gun and dies.

I appreciate the comments above, some have touched on things I did not mention. EX: Turning the case in sequential steps during the seating process. I adopted that practice and still do so when in pursuit of low R.O., though I did it with a single 180* +/- rotation in two steps. Maybe 1/3's is more better.

On another point, I don't as a matter of routine do this with all my loads for all guns. I've found some guns do not benefit from the effort and some, due to their general application never will. Think military autoloaders long in the tooth, or perhaps other guns that by general use or other circumstances seldom draw down on any but short range targets. If my M1 Carbine had a bottle neck case I still would not bother. OTOH, if I were shooting LR competition with a black rifle I would at least take a look, be it jacketed or cast/swagged bullets.

My theory of life in the shooting world is simple: If you have an entire deck of cards labeled as 'variables', some of them will null others but most will increase dispersion. At long range I think the evolution is worse that a simple linear increase of dispersion. Probably not exponential, but it won't be your friend in any case. Vertical dispersion due to velocity variations comes to mind. It matters when one starts shooting across zip codes, area codes or time zones. You get a chance, kill a variable for the cause! R.O. is one of them...

[detox]

Like 44man says "Can't measure on a cast boolit since most are not round so measure case necks".

It is lots easier loading concentric ammo using concentric jacketed bullets.

How well a cast bullet fits throat and bore is more important. Support your local bullet

[Digital Dan]

Respectfully disagree regarding the concentricity of cast bullets. Having read the objection several times in this and other posts I just finished exploring that point.

Evaluation done on a RCBS Casemaster with the following bullets cast or swaged:

1. Ideal 257283, sized to .258" w/ Lee push thru sizer. Bands on either side of the grease groove indicate R.O. of .001" or less for three bullets.

2. Lyman 311041 sized to .309" w/ Lee sizer, same results with 3 bullets.

3. Lyman 287405 sized to .285" w/ Lee sizer, R.O. .001-.0015 on 3 bands X3 bullets.

4. Custom Dave Mos .403" 350 grain for a BP bullet gun, unsized, .0005" or less R.O. On 3 bands X 3 bullets

5. Hammer swaged .510" smooth paper patch bullet for another BP gun did .0005" or less for 3. Bullets.


I am am not a particularly gifted caster or deeply experienced. Perhaps unsized bullets will indicate greater variations of roundness but it is perfectly clear to me that cast bullets can be evaluated properly after loading. It has nothing to do with rocket science.

[44man]

Luck to get a perfectly round cast boolit. A fully sized portion maybe.

[williamwaco]

Larry + 1 except my tests were with .223

Lesson One. Operate the press handle slowly.

[Digital Dan]

Luck to get a perfectly round cast boolit. A fully sized portion maybe.


Well, perfection is little more that a goal for some and used up all my luck in SE Asia some decades back. 5 bullet styles x 3 each is a fair sample for statistical purposes in my opinion and variations of the magnitude shown are insufficient to cloud R.O. evaluation for loaded cast bullet ammo. Whether or not one wishes to pursue such things is not my decision.

[HangFireW8]

My experience with jacketed is the smaller bore, bottleneck, high velocity cartridges are most sensitive to eccentricity, not coincidentally these are the most potentially accurate.

Also short bullets are more sensitive since they are less self-centering.

Testing all cartridges can potentially eliminate fliers. Testing all cartridges is a PITA.

If you have a bad sizing die, testing will help you sort it out. I have moved to minimal neck sizing with either lapped or bushing for all my bottleneck sizer dies. The expander becomes a minimum size checker instead of expanding. A huge benefit is longer case life. Much longer than conventional neck sizing. It is crazy how much a standard FL or NK die sizes the neck.

[CHeatermk3]

The RCBS concentricity gauge--possibly the most expensive tool I have ever purchased...not in price of the tool but in $$ spent afterward. Prior to getting it I just rolled my loaded rounds on a flat surface and gauged w/mk1 eyeball. Good enuff for hunting in the woods where 80 yds is a long shot but for 300+ yds prairie dogs not so much.

[MT Chambers]

Forster Co-ax press with an inline seating die.

[44man]

My experience with jacketed is the smaller bore, bottleneck, high velocity cartridges are most sensitive to eccentricity, not coincidentally these are the most potentially accurate.

Also short bullets are more sensitive since they are less self-centering.

Testing all cartridges can potentially eliminate fliers. Testing all cartridges is a PITA.

If you have a bad sizing die, testing will help you sort it out. I have moved to minimal neck sizing with either lapped or bushing for all my bottleneck sizer dies. The expander becomes a minimum size checker instead of expanding. A huge benefit is longer case life. Much longer than conventional neck sizing. It is crazy how much a standard FL or NK die sizes the neck.
Very good and so hard to explain. I found that about 60 years ago. Bushing dies the best ever until the rest of the case needs FL again to chamber but still need minimum neck sizing.
I will give you 10 out of 10 stars.

[44man]

Larry + 1 except my tests were with .223

Lesson One. Operate the press handle slowly.
Yes, it takes me longer to make one round then others use for 100. Had a friend here to load and he was slamming the press until I stopped him. Famous guy with books.
There are "loaders" and "hand loaders."
A very few actually investigate a problem to the finish. Think marks on the dies means they work.