grouping issues

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by clem81, Dec 16, 2012.

  1. clem81

    clem81 Well-Known Member

    Apr 4, 2009
    i have a new 243AI, that i have broke the barrel in, it is a 1-8 benchmark. and i am shooting Sierra 85 Gameking, and 90gr Bergers and 80 gr Sierra Flatbase. 44-45 gr 4350. the issue is in a 4 -5 shot groups ill put 3 on top of each other and 1 or 2 will be out 1/2 in or more. i have tried differnet depths with bullet seating. i have checked the bullet rounout .002 nmax. Now my thoughts are it is very short throuted. so i am thinking it needs to be longer so it starts into the rifling better. Is it possible the buleets base is being effected because its so far in the case. Any thoughts
  2. Lefty7mmstw

    Lefty7mmstw Well-Known Member

    May 13, 2012
    I'd have the throat lengthened a bit so you can get 100 grain+ bullets at the base of the neck without jamming into the rifling. 8" twist is dang fast for sub 100 grain pills in the 243 or 243 ai. That said, have you tried a bit faster powder?? I've seen 243's really shoot well with vit 540 or I4064 and 100 grain pills. You won't loose that much velocity either.