I use an electronic scale and weigh 5 at a time for 3 or 4 weigh ins. I then establish the average weight per case, weigh them individually and then cull anything on either side of the bell curve. I normally prep brass a hundred at a time as the average NM course goes 88 rounds with sighters. Trim your cases first to take any variables out of the equation.
The 1 in 9 twist is perfect for the 69 grain match bullets.
I and many of my shooting team buddies find the GI 5.56 brass to be preferable to most civilian brass in the M-16/M-4/AR-15 rifles. A few guys will use Winchester 223 cases at 600 yards, but I've never noticed any difference in score or performance when I've tried that. I was also a big fan of GI Lake City match cases back when I used the M-14 in 7.62 NATO calibre. That rifle is hard on brass (unlike the AR-15) and the civilian cases that we sometimes used at long range only lasted a few shots before the web thined out and we tossed them. When the Army adopted the M852 round with the 168 grain MK to replace the M118 Special Ball round, we just quit bothering to reload for the M-14.
I wish my 1 and 9 twist Winchester barrel shot the 77 grain bullets well, but they start to wobble between 100 and 200 yards and thus make my Winchester Model 70 a light bullet rifle. It's OK on reduced courses of fire (at 100 or 200 yards) or at the early season 200 yard off hand (standing) matches of usually 100 rounds. I can use use almost any bullet under 70 grains with success then and the wind bucking ability of the heavy bullets really isn't needed until 300 yards or so.
US Army Distinguished Rifleman
Washington State Distinguished Rifleman
NRA Police Distinguished Expert
Last edited by Scharfschuetzer; January 31, 2012 at 06:10 PM.