Recommend 284 twist and contour

Discussion in 'Gun Project Questions & Gunsmithing' started by Dave in WI, May 16, 2018.

  1. Dave in WI

    Dave in WI Runs with scissors Silver $$ Contributor

    Dec 12, 2014
    I have a customer wanting to build 7mm-08AI on a 700 action. Plans are for a barrel no longer than 20" and he will be running it suppressed most of the time. Now, I've already discussed with him the negligible gains of the AI in a 20" barrel, so please keep that out of the discussion. :) He just plain likes the idea of the cartridge. He plans on experimenting with the Federal 155 Edge TLR bullet, so looking for suggestions on twist rate. Most readily available 284 barrels appear to be 1-9. The 155gr will probably be the heaviest he will play with. Will the 9 twist suffice for this.
    Also, we are looking for the muzzle diameter of around .750" when finished at 20". What contour barrel will get me there without further contouring?
  2. rgc54

    rgc54 Silver $$ Contributor

    May 19, 2006
    Number 4 or 5 contour depending on manufacturer. 9 twist would be good for up to at least 162 grain.
    Dave in WI likes this.
  3. yukonal

    yukonal Silver $$ Contributor

    Jul 14, 2008
    Agree completely. I have several 708's and 284's...both in #4 and #5. All 9 twist. I shoot 120 to 180 gr bullets, and all shoot very well. Shouldn't need more than a 1" shank. Leave the rest on the barrel.
    284winner likes this.

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