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My goal was to duplicate NATO 7.62x51 ammunition. Specifically the M80 and M118 catridges.
I already had the pull down bullets (for the M80), a ton of LC once fired brass, and CCI primers in two flavors.
So I ordered 8-pounds of "WC-846" military powder, which is what the NATO specification calls for. While I was waiting on the powder, I did some more in depth research. In this case, I am very glad I did.
I got the M80 nailed down today, so that is the context of what follows . . .
The NATO spec calls for 46.0 grains of WC-846. But the reading I did conveyed to me that it just ain't that simple. Powder is manufactured to a NATO specification. In this case 50,000 PSI, 78 feet from the muzzle with a resulting velocity of 2750 FPS. Notice there is no charge weight listed in that specification.
Turns out what happens is that unlike commercial powders, military powder can be very inconsistent from lot to lot. What the factory does is get a railroad car (or 100) full of a given lot of powder then test that powder to accurately determine the required charge weight. When that lot is used up and they get another one, they do the same thing again.
So . . . the absolute fact of the matter is that whoever wrote the military manual for small arms cartridges must have pulled a few bullets and weighed what was in those specific cases then written that number down in the manual.
Having learned how this thing REALLY works (at least according to the Internet), I figured I better start conservatively and work up to the velocity specified - as I can not measure chamber pressure beyond "reading the brass" after the fact.
I know; shocking. Me and the word "conservative" in the same load data post. The truth is I didn't want to risk hurting my M1A.
So . . I loaded up three rounds with 44.0 grains and went and chronographed them.
2749
2743
2749
Again; it was supposed to take 46 grains to do that! I am more than a little happy that I didn't just throw 46 grains in the cases and call it good.
Just for giggles, I had some genuine NATO factory built M80 on hand so I can a round over the chrono. 2842 FPS.
Obviously I do a better job loading to specification ammo than Lake City does.
yeah, I am proud of that. But my point isn't to brag believe it or not. It is to point out that if you get inclined to load genuine military surplus powder be darned careful !!!!!!
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Originally Posted by Airgator0470
