I ran across some PMP brass yesterday, and noticed that the 26gr of Varget I was putting into it filled it right to the top and that I needed to compress the powder in order to fit the bullet to the correct OAL. The case was trimmed to the correct length as well as the federal, win, PMC, and Remington that I was reloading. For the hell of it, I measured the ID of the neck and somewhat of the OD at the base with hardly any difference between the different cartridges. Then I weight them, and saw that the PMP brass was about 30 grs heavier in comparison. Anybody experience that before?

Needless to say, I set the PMP brass off to the side. Now I would assume since the brass is heavier, I can only assume it that it has thicker walls. With that being said, it should be able to handle the 26grs of Varget with it being compressed by the bullet fine.

An thoughts on that one?
Thanks.

You neglected to say which bullet you use or at least the bullet weight.

Irrespective of that, my thought is that you MUST redo your load work up with that new brass. The case may be able to handle the load, but the pressure is going to be way up with the attendant problems.

Added: I once used Winchester brass instead of the regular LC brass I was using at the time, by mistake. I pierced primers right away. I had to withdraw from the match, and the go home and pull 96 or so bullets. Yuck.

According to Accurate Shooter, the PMP .223 bras is the heaviest of all the ones checked, but not by 30grs, more like 10-12 grains. 30grains is a LOT for a case that weighs around 92-96 grains.

It is a 55gr bullet.

I had 6 for sure that were consistently measuring about 30 grs heavier.. Maybe just a fluke in the manufacturing process. IDK that's why I thought I'd ask and see if anyone else has saw this.

yeah, understood. I would really measure those again and post the weight, not just the difference; the actual weight. According to what I know, that should be upwards of 120grs.

You might also will them with water and post the weight of the water needed to fill the case. That could be good for giggles also.

Case weight is only a "ball park" idea of the case capacity as you can see below.

Also Lake City brass is harder than any .223 case and has a thicker flash hole web. Meaning these cases primer pockets last longer before stretching and becoming over sized.

Using the chart below and Quickload there will be 6,000 psi difference between the top Lake City and the bottom old Lapua cases. This is using 25 grains of H335, a 55 grain Hornady FMJ and 2.6 grains of H2O capacity difference.





Bottom line, I buy bulk once fired Lake City cases at a fraction of the cost of new .223 brass. And end up with very uniform cases in weigth and volume And on top of this the Lake City brass is made Ford Truck Tough.

How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests

http://bulletin.accurateshoote...base-hardness-tests/

Yes, Lake City strikes the back end of the case twice to increase its hardness, when they crimp in the primers.

The chart you show is exactly the one I was talking about at Accurate Shooter. As you can plainly see, the PMP brass stands out by being the heaviest one there, but by about 10grs, which is why we are surprised by the reported 30grs of extra weight, and why I urged a reweight and the report of the exact weights found, not a delta.

Some MFG change suppliers if they are not the ones making the brass. My neighbor was shooting some Hornady or Winchester, 1/2 were NATO stamped the other were not. The NATO stamped ones were 20-25 gr heavier than the commercial. He though since they were the same mfg they should be the same, Wrong. He has since taken my advice and bought 1000 LC brass. All he had in brass was small lots of mixed mfg (8) which is hard to load and get consistent ammo when the case volume is not the same.

OK, so I just weighted a few PMP brass and found that the least weight was 15 gr from a Remington, and the most was 28gr.

122grs for the high end and 109grs for the low end. I didn't expect this must variation with the same head stamp. Now I am assuming that this is thicker but a low end quality brass.

So going back to my original question, would this be still ok to handle the same pressure with the compressed load as to a non-compressed? I have re-loaded 22 hornet with a compressed load and never had a problem, been doing that for years. Granted it's a smaller round but...
My grandfather used to tell me, "books are a suggestion, they don't test the guns to the maximum pressures of the books, they hammer the shit out of them until they fail and then reduce it. Your guns can handle at least 3 times the pressure of the books" Now this is coming from an old timer that reloaded many many moons before I was born. I tend to agree but that brings in pre-mature failure of the weapon.

Thanks for the info bigedp51, and reading that article was very informative.

That much change in weight (heavier) I would reduce the load and work back up. Normally I find LC and Lapua brass to differ but only 0.1gr, depending on year of LC.

Also that difference is enough to effect accuracy too. So dropping the load a 0.5gr and working back up will allow you to find your load with the same properties of your original one.

quote:

Originally posted by Blue68f100:
That much change in weight (heavier) I would reduce the load and work back up. Normally I find LC and Lapua brass to differ but only 0.1gr, depending on year of LC.

Also that difference is enough to effect accuracy too. So dropping the load a 0.5gr and working back up will allow you to find your load with the same properties of your original one.

And after more research and what I have gathered on here, I think that is what I am going to do. I really think there was just a fluke in the manufacturing process on this batch. I am surprised at the variation as well.

Even the LC varies from years to years. But their close enough to use the same load. Ill I have to do with LC is tweak the OAL by 0.005-0.010" I have 3 years that are the same and 1 other that different, not counting the older brass <2007. All my load data was setup using LC 15 as my std.

Look for the NATO stamp. If it has one it will be heavier than the commercial.