So I have discovered a problem with my entire supply of 9mm subsonic ammo. These were loaded with 4.2grs of WSF, CCI 500 primers, and Zero brand projectiles; in mixed commercial brass, with a 1.130 COAL. EVERY SINGLE round has been case gauged, to ensure that they will chamber. I initially worked this load up for my 5" 9mm AR, with a suppressor in 2007, and have had very good success with this recipe, up to this point. A couple of weeks ago I opened a new can of 2000rds, that I produced in 2010. I immediately noticed a loss of accuracy from my AR. Since that time I have run these through my chronograph and verified that the velocity is where it is supposed to be, and that my standard deviation is also within tolerance; so that has ruled out bad powder or primers. I have also purchased some factory AE 147gr rounds, and run those through my AR, which produced excellent results; thus ruling out a bad barrel or poor shooting on my part. The bullets all measure .355, they all weigh ~146grs, and measure .376 at the mouth after being loaded. I have come to the conclusion that for whatever reason my AR no longer likes the Zero brand bullets. Not sure if it is composition, or design, or what; but at 50yds, I can barely keep 20rds inside a 10" circle. So what the hell? Mathematically, everything is where it is supposed to be; yet my results are completely unacceptable. The only thing that could have changed, and I know this is a stretch; is possibly the amount of buildup in my suppressor. Could this possibly be causing some kind of turbulence inside the can, resulting in an unstable flight path with the round nose bullets; vs. the flat nose factory loads? I'm at my wits end. Please help...
R/,
Matthew A. Roddy
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Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.