In the heyday of the 7.62 NATO round's match winning and record setting successes, here's what was uised inside their chambers to do that.
Cases..... New cases always shot the most accurate. Reloading fired ones never did well as the rifle's bolt faces were never squared up with the chamber axis. Firing any case with an out of square case head makes the barreled action whip at different angles for each shot. If really good accuracy's your objecive, use only new cases. Otherwise, a standard full length sizing die set up to move the fired case shoulder back no more than 3/1000ths is best.
Powder..... Nobody used ball powders to shoot well. Some lots of Lake City Arsenal match ammo was loaded with ball powder and it never shot all that accurate. 4895 was the best stuff used by arsenals as it metered well in high speed reloading machines. But the top scores shot by both military and civilians using M14's, M1A's and M1's were shot with commercial match ammo with IMR4064 (sometimes IMR3031) powders. Excellent examples:
43 to 44 grains of IMR4064 under a 165 to 175 gr. bullet
42 to 43 grains of IMR4064 under a 180 grain bullet.
Primers..... All makes and types of primers were used. The Federal commercial match ammo was about the best available and their 210M primers did just fine. Any medium to mild primer will do fine with the milder ones typically producing the best accuracy.
Bullets..... Best accuracy's made with bullets a few ten thousandths bigger than the barrel's groove diameter. Sierra's are probably the most accurate.
Testing loads is where most folks fall short of picking the best load out of several from their reloads. They don't shoot enough shots per test group for it to be meaningful. Shoot at least 15 shots per grouip; 20's better. And judge groups by their largest size; forget the tiny ones. You may wear out your barrel trying to shoot another very tiny group you did once. Top competitors would rather have ammo for their MXX service rifle that shoots no worse than 4 inches at 300 yards and no better than 2 inches than a rifle that shoots up to 5 inches at 300 but sometimes shoots 1 inch at 300. They'll miss their aiming point the least amount with the 4 and 2 inch loads. compared to the 5 and 1 inch ones.
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