Sorting head stamps and case volume . . .

[Prof Young]

Loaders:
Spurred by a discussion in another thread I have to ask how sorting head stamps can really make any difference?

Suppose I have a formula to put X grains of powder under Y bullet. I'm going to use that formula for Winchester cases and Remington cases and PMC cases etc.

Even if there are differences in case volumes the difference must be minute from case to case in a given caliber.

So I ask again, what difference can sorting head stamps really make. It isn't going to change the formula one uses.

Live well, be safe
Prof Young

[OnTheFly]

Pistol plinking and/or action pistol matches, it is not necessary.

Pistol bullseye, it would be very important.

Rifle plinking, it is not necessary.

Rifle competition (high power, action shooting, bench rest, etc.) it would be very important. Note: much of the action rifle shooting is 25 yards to 100 yards, but may be further out. So you would need to know how your rifle/ammo combination performs out to those distances.

Otherwise, in the realm of safety, the differences in case volume is not going to have a significant change on pressures.

Fly

[Jim243]

The volumes buy brand change only slightly, but even a 0.2 grain difference in powder or pressure can make a big difference when measuring distance on a target by mins of angle or millimeters, The difference between 0.32 MOA and 0.25 MOA is winning a match or just losing one.

You tell me, if it is worth taking a few min to sort the cases by head stamp and weight to insure constant volume in the case?

The choice is yours.
Jim

[Nick_C_S]

As a pistol only loader, I do it for 38 Special. But mostly because I buy my brass new, or from Winchester White Box factory ammo. So I only have a couple types. Otherwise, if I had a bunch of range brass, I probably wouldn't bother. I do believe it gives me a more consistent product. Which is important in action shooting sports when you've made ammo that is just above Power Factor.

The only other instance where it concerns me is with full throttle 9mm ammo. The 9mm has such a small internal space, that different brass can make a considerable difference in pressures. When I load to the top of the scale, I stick with the same brass every time.

[Jay24bal]

Depending on the application, it can be very important. Personally, I only do it for my precision rifle ammo, and here is an example of why:

For my 243, I use Winchester cases. The lot of brass I have varies in weight from 158 grains up to 162.5 grains, a 2.8% difference.

While 2.8% may not seem like a big number, look at it from a muzzle velocity standpoint when shooting at longer distances. Using the ballistics calculator on my phone here, a 2.8% reduction in MV at 600 yards results in the hit being 5 inches higher/lower than it should be (yes, I realize it is not a 100% direct correlation between case volume and MV, but for arguments sake, let's assume it is close enough to illustrate why a 2.8% difference matters). And that is only 600 yards, the drop gets exponentially bigger as the distance increases.

To truly illustrate the importance, go weigh a random 243 Win case. I only use Winchester cases so I have nothing else to go on, but if a Remington case weighs 166 grains, double 2.8% to 5.6%.

So if shooting at 100 yards and going for minute of deer, I admit that sorting and weighing cases is not a good use of time. But when shooting at distance where accuracy is your goal, that 5 inch miss is the difference between punching X's and winning, and shooting a bunch of 9s and coming in 20th.

[condor bravo]

If we are talking about rifle cartridges, let's say especially around '06 size or so, one consideration can be case neck (bullet release) tension. Of the big three, Federal brass due to being thicker and heavier will usually exhibit greater bullet release tension, then followed usually by Remington and Winchester. My favorite when I can get it is Federal but it is often not available as a stand alone component (unless perhaps once fired). You usually have to start out with factory rounds. New Remington and Winchester brass are usually easy to come by. Bullet release consistency could enter the accuracy equation.

[higgite]

So I ask again, what difference can sorting head stamps really make. It isn't going to change the formula one uses.

No, it isn't. But, it is going to make that formula produce more consistent results from round to round. Target rifle shooting at 500 yards, it can make an appreciable difference. Self defense pistol practice at 1 to 15 yards, not so much.

[OnTheFly]

Originally Posted by Prof Young

So I ask again, what difference can sorting head stamps really make. It isn't going to change the formula one uses.

As myself and others have suggested, it depends on your application. Precision rifle, if you REALLY want to shoot the wings off of a gnat at 200 yards, you will work up a formula that is specific to the case headstamp. For this application you will be sorting cases, weighing every bullet, hand measuring each powder load, hand prepping each case, etc. to put bullets into the same hole off of a bench rest.

So...yes...you will have a formula specific to that headstamp.

Fly

[F. Guffey]

Spurred by a discussion in another thread I have to ask how sorting head stamps can really make any difference?

Sorting head stamps: Can it really make any difference? Long ago and forgotten a shooter/reloader purchased 500 cases, all from the same lot, with the same head stamp etc., etc.. First he sorted, then resorted and fired then sorted the fired cases. Out of the 500 he selected 47 cases. He found he could index cases that appeared to produce flyers. He found he could match the reject cases to produce good groups. He had two criteria, he matched cases to head stamps, after that, he got serious.

Then there is "If a reloader goes from commercial cases to military cases reduce the powder 10% because!? military cases are heavier and heavier makes the case thicker". And that is only half true. There is no shortage of military and commercial cases around here, I have military 30/06 cases with .200" case head thickness from the top of the cup above the web to the case head. When I compare the surplus case head thickness with a R-P commercial case of the same period I find the R-P case head thickness to be .260". Meaning the commercial case head was thicker than the surplus case head. That should cause someone to wonder: What does that have to do with anything?

If the Surplus case has a thinner case head but is heavier the case body must be thicker, and, if the commercial case has a thicker case head but is lighter the case body is thinner. If that is true the diameter and length of the powder column is different for both cases.

Do I sort by head stamp, yes I do. Do I weight cases when loading heavy? Yes I do. Like the old poem goes: "The saddest words of verse or pin is "Oh what might have been". Sad words, "It must have been a double charge".

If a reloader knew the weight of the bullet, powder charge, case and primer, the reloader could determine the gross/total weight of the round after loading.

Sorting, when I finish tumbling I want the same 20 cases back together in the same box.

I was sorting and cleaning cases a few days ago, I found two Browning 30/06 cases Is my box of Browning cases missing 2 cases?, or did I find 2 Browning cases I did not know I had. I stuck the Browning cases in with a partial box of Super X 30gov-1906 cases.

F. Guffey

[jmorris]

As above it depends.

If you are using the ammunition in a manner that does not require ultimate precision (like ammunition for plinking, 3 gun, USPSA/IDPA and most hunting applications) it won't matter that much.

If you are trying to reduce the diameter of the hole your one hole groups make in benchrest, you are trying to reduce tolerance stack and any variable you can control.

[BigJimP]

In handgun calibers I don't think sorting by head stamp is important at all...

I use good quality components...especially in terms of the bullet / a true jacketed bullet like Montana Gold varies only a few tenths of a grain from bullet to bullet..../ cheaper plated bullets, especially ones that are electro plated ...in a 230 gr bullet, I've seen vary as much as plus a couple of grains and minus 5 grains...

[Clark]

I have got groups less than 0.5 moa 5 shot at 100 yards with mixed headstamps.

Just because I cannot not resolve or even detect the difference due to some handloading accuracy ritual, does not mean someone else cannot detect it, someone who is a better shot, better rifle, longer range, and more shots per group.

It depends where you are in the learning curve. If you wonder if a new car could get you a date with some girl, but you have not showered or changed your clothes in a month, then the new car contribution to mating rituals is not the dominant driver in the equation.

Likewise if you have 5 inch groups, matching headstamps is not going to make a noticeable improvement. It would be better to look at Copper fouling, wind gusts, jerking the trigger, and checking the scope bases.

[Unclenick]

Originally Posted by Prof Young

Even if there are differences in case volumes the difference must be minute from case to case in a given caliber.

Actually that's not true with some chamberings. The worst offender is 300 Winchester Magnum. QuickLOAD's author found them so different among manufacturers that he actually has separate files for several of the brand names, not feeling it's right to treat them as the same exact chambering. He showed Remington brass with 88 grains of case water overflow capacity and Norma with 95.5 grains of case water overflow capacity, originally. I think Remington maybe went up to 89 grains in the last database update (not on that machine to check at the moment), but it could always go back the other way with future lots.

If the brass had the same exterior dimensions and were all made of the same alloy, that would be about 64 grains difference in case weight between Remington and Norma. The most I've seen in .30-06 is about 25 grains. In .308 Winchester it's been about 30 grains, though that grows to 40 if I take other people's measurements into account.

An old rule of thumb developed by Wm. C. Davis, Jr. in the 60's was it takes about sixteen grains difference in case weight to justify one grain difference in powder charge, with the objective being to keep pressure constant. I try to load for sweet spots that are in a band that allows at least 1.5% and preferably 2% change in charge weight before the rifle moves off the sweet spot. Staying on a sweet spot is more about keeping barrel time constant than pressure, and I find a factor of 14 grains of brass to 1 grain of powder comes closer than that. In the .300 WM, that works out to about 4.6 grains of powder charge difference between the Remington and Norma cases. In .308 Win it works out to about 2 grains difference from the lightest to heaviest cases I have. Its around 4-5% of charge weight in that chambering, so its enough difference to move me off a sweet spot if I don't adjust for case differences that great. It is, however, not enough to make a load dangerous if I fail to do it, as long as the original load was within SAAMI limits. If the original load was developed in a light case and was right on the edge of giving me sticky bolt lift, then the difference could be an issue for gun wear if not safety from case ruptures in some guns with a lot of unsupported case head. But that's not the norm.

In real life, case weight is never an exact indicator of water capacity unless the cases are all from the same lot. Outside dimensions of the head have to match. The density of the alloy used to manufacture the cases has to match. It's not just a scale thing. I weighed a few different headstamp .308 cases one time and then measured their water overflow capacity and found the weight predicted their water overflow capacity to about ±20%. The .223 page on 6mmBR.com as a table of a good number of different headstamp cases they weighed and measured the case water overflow capacity of. There's a correlation, but like with my .308's, it just isn't very tight. I plotted the data from that site, below.



The other factor with weighing is it can sometimes tell you other things about the brass. In the example below, I weighed some Lapua cases in .308 Winchester, and arranged the data in histograms. You can see from the data that there were pretty clearly two different sets of tooling making the cases. That let me sort them by tooling to check if one set had a little bit better concentricity than the other so I could decide which tool set's output would be the match brass and which would be the load development and practice brass. Different tool sets may give different head thicknesses or different outside head dimensions that can affect the correspondence to case capacity. I was not, in this instance, able to get a significant difference. But since I had the output of the two tool sets segregated already, I kept them that way. Used one half then and the other half later. Only made a difference to the OCD side of me.



If I sorted by headstamp first and then by weight, a 1.4 grain spread would equal 0.1 grains of powder difference, and I don't normally dispense more accurately than ±0.2 grains, except during load development, so I'm not normally going to see a difference on cases sorted to the nearest grain.

If I have a bulk brass purchase that I want for an accuracy gun, I usually sort it by wall runout first. That matters a lot more, IMHO, than a few grains difference in weight. Then I sort by weight to look for indications of different tooling. Once separated by tooling, separating by weight then usually doesn't accomplish much as a bunch of brass off the same tooling for the same lot tends to be pretty close together in weight already.

If you want to check for tooling differences by weight, rather than Excel it as I did with the Lapua, just get a big piece of paper and write the weight range down in tenths of a grain and weigh and place each case over its weight on the paper. Groups of weights then become quickly apparent.

[Clark]

I have measured 300 WM cases and they were all over the place, but did not bear much resemblance to the QL library for those brands.

Reminds me of a mechanical engineer that wrote ADCNs to fix a specific problem in tolerance build up, and the next batch of fighter plane power supplies had a completely different problem. There should have been a select in test procedure to shim to fit.

Gotta be careful what I say, Helmut reads the forums... I would pay $3k/ year for Quickload if it cost that much. I love Quickload.

[308Loader]

I am still kind of new to loading. With .308 win cases I found that from head stamp to stamp the case volume differs greatly! what one might consider a mild safe round in one head stamp might be max in another. I think some stamps lend themselves to being reloaded and some are fire and forget. Not sure why, but I have loaded some herters and ppu brass that I bought new and fired once. they showed signs of insipient head case separation marks on the first loading at a low powder charge, also cratered primers, sticky bolt... I sort my brass by head stamp so I know that if I have a brick of 50 that I can expect the same or similar out of all 50. After sorting by head stamp some say to re-sort by weight, haven't got their yet.

[catgunguy]

Thank you Unclenick for the info on the different machines turning out the brass. I have noticed lots with weights in a set as you have shown and I didn't realize that was the reason. It makes perfect sense now that you have pointed it out.

[Prof Young]

Loaders:
Thanks. Lots of great info here and I see the difference sorting can make. When looking for absolutely consistent performance case capacity has to be the same for the internal pressure to be the same. I get it. If I ever become a competitive shooter and get serious about reloading for accuracy, sorting head stamps will be part of what I do.

Live well, be safe
Prof Young

[cw308]

Remington & Winchester brass are about the same in volume. I was reloading with that brass for years, then I switched to F/C & ADI brass witch is mutch thicker. Had to reduce my loads by 1. grain. It does make a big difference

[F. Guffey]

Remington & Winchester brass are about the same in volume.

Could be a change in brass that I am not caught up in. WCC, WRA, Winchester, WWC are the lightest 30/06 cases I have. The thickest case heads I have are R-P.

Other 30/06 cases I have are Super Speed and super X. Because I load them with matching case heads I do not find it necessary to weight the cases. Many of the cases are 70+ years old.

F. Guffey

[44 AMP]

So I ask again, what difference can sorting head stamps really make. It isn't going to change the formula one uses.

the formula? no, probably not, but the AMOUNT of powder could be changed, due to differences in case capacity.

I'll tell you one place it absolutely makes a difference between "headstamps", and that is forming .44AMP cases from GI brass. I have a small quantity of commercial cases, and the difference in case capacity between them and brass formed from GI cases means I MUST reduce top end loads by a couple of grains of powder, to stay within acceptable pressure limits.

Sorting commercial cases by headstamp (R-P vs Win, etc) usually isn't as much a matter of charge wt/pressure safety, but more a matter of consistency, and consistency is the fundamental of accuracy.

[Mike / Tx]

I've also found, and I can't find the post now, but someone else also pointed it out a while back, some 9mm cases with what looks like they have a portion of a smaller caliber case shoved into them. It really isn't another case but it does really reduce the internal capacity compared to other brands.

I load a LOT of ammo using Bullseye and would not probably have been happy using one of those with a couple of the higher pressure loads. Not that I am over book by any stretch, but considering how temperamental a 9mm is on seating depth verses pressure spikes with some of the faster powders, or longer bullets, I don't want to take those sort of chances.