I was reloading some military surplus brass in 30-06 yesterday and noticed that one in my block was nearly full of powder and the rest had substantial room left in them. I thought maybe I had mis-weighed the powder or the powder thrower messed up.

Of course, I had to find out what was going on. I found that this piece of brass had significantly less volume/capacity than the other brass. The brass in question is marked PS 74 and from what I can find out, it is from Korean made 30-06 ammo. Below is what the powder weighed from some 30-06 cases rim full of IMR4350. (All were FL sized and trimmed.) Three are commercial and three are military.

Fed -- 62.9 gr

PMC -- 62.5 gr

Rem -- 62.0 gr

HXP 70 -- 62.3 gr

LC 69 -- 61.7 gr

PS 74 -- 55.0 gr

That is about a 10% reduction in volume for that last case. Of course, I caught it and didn't load it, but what if I had loaded it with the same charge of powder used in the other cases? Wouldn't there have been a substantial increase in pressure in that cartridge when fired? Would the pressure increase have been enough to be dangerous?

I rummaged through some of my other military brass and couldn't find any more with this head stamp. I wonder if all the PS 74 head stamped brass would have had such low capacity or was this just a fluke? Has anyone else run across something like this when using military brass?

Finally, could you well seasoned reloaders of military brass provide words of wisdom when it comes to reloading military brass to those of us less experienced in its use?

Red C.
Everything I say is fully substantiated by my own opinion.

Red C. A case filled to capacity will cause higher pressure, you could create a similar situation by seating the bullets deep into the case. In the future I would recommend matching cases by head stamp, with military case that would mean matching head stamps by year, to me the advantage is recognized when tumbling and separating cases by head stamp and and by year.

Loading military brass has always been about thicker verse thinner, that old saying is half true, because military brass is heavier most believe the case has to be thicker. The head of the military case is thinner and the case body is thick, impossible for most to measure because the cup in the bottom of the case is concaved but when measured the military case head measures .200 + or - a few, the R-P commercial case head is .260 + or - a few meaning the case head is thicker than military brass with a thinner body.

The difference? The colum of powder in a military case is longer but thinner in diameter than the column of powder in the commercial case, the column of powder in the commercial case is shorter but larger in diameter.

As to the one case with reduced volume, had you weighed your cases and if the reduced volume was caused by brass in the head of the case and in the body of the case the case must be heavier, For the most part when prepping cases I use the RCBS case prep canter with a bore brush in one of the 5 positions meaning the reduced volume on the one case could have foreign material in the case that is displacing the available volume.

I loaded 250 30/06 cases on a progressive press, after loading I weighed all 250 rounds, there was 17 grains difference between the heaviest and lightest, the loaded rounds that were light were Winchester cases as WCC, WRA and Winchester. Had I not weighed the cases before loading I would have no way to determine what caused the 17 grain spread. The weight of the components should = the weight of the loaded round.

F. Guffey

quote:

but what if I had loaded it with the same charge of powder used in the other cases?

On firing, the round could have been over pressure, the web area would have expanded, along with a loose primer pocket. Saw this online, in 308 with PV brass with a starting load. We all thought he miss weighted the powder, but more testing showed it was a brass problem.

There wasn't some sort of foreign object in the case was there? I ask because once I loaded up a block of cases and when I eyeballed them, one had a much higher powder level. I went through all of the steps you did only to find out that some kind of wee dirt dauber type varmint had built a nest in it.

I've run into dramatic differences in case capacity with the .308 mil-surp brass....but not (yet) with .223 cases.....

There's no reason one might not see the same thing as the .308 variation in the .30-06 cases.

I no longer have any mil-surp .308 or .30-06 cases....but have a lot of mil-surp .223 brass.

quote:

LC 69 -- 61.7 gr

PS 74 -- 55.0 gr

I've seen a gr or two difference. Never 10%. First thought I'd have is something in the case.

I've pretty much lost or retired all my 06 military cases. So far my 223 cases have been close enough I don't separate them.

I've never seen more than maybe 1.5 gr. difference in US GI cases and that isn't likely to move a normally safe load into KABOOM territory. Never tried any non-US stuff.

Like someone mentioned one case that is showing less volume more then likely had something stuck inside it. Often I've found stuck tumbler media in my cases so I'll watch out for that.

I like military 30-06 cases for the thicker neck when forming them to other caliber. Then I can neck turn them to the precise neck fit that I like.

Until you are measuring brass that has been fired in your rifle the volumes may not mean much.

Once they have been fired in your rifle and sized in the same die the volumes will be comparable.

The brass didn't have anything stuck in it. I found two other pieces with that same head stamp and they had low volume as well. Must of been that lot of brass from that manufacturer.