If you have a 1:8 you just about have to have a Wylde Chamber with 75's and heavier!

I have one of the Savage 12 single shot's with a 1:9. With 75 A-max and 77 Berger VLD & Hybrids, I get away with a standard 223 chamber. Using Lake City virgin brass a Remington 7 1/2 primer and 26 gr Varget (and seated to the lands long). This gun and ammo earned the name "The M&M Gun", from picking off M&M's at 200+ yards. With the BR stock (pillar bedded) this set up does 3" at 1000 yards, with the factory varmint stock, it does 5" at 1000 yards. This load won't think about fitting in any type of magazine, and is really too much for AR actions!

For an AR plinking load, I loaded 26 grains WW748, CCI primers, match prepped mixed brass and old (1984) Winchester FMJBT 55 grain bullets. In my 1994 Bushmaster AR-15 A-4 with 6.5-20 Veri-X III Scope of a rest 3/8-1/2 inch at 100 yards. This load does better in my Cooper 21.

Stay safe!

Ivan