New build-chamber and barrel contour questions

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by sliceman, May 24, 2012.

  1. sliceman

    sliceman Member

    Messages:
    12
    Joined:
    Apr 12, 2010
    I am planning my first long range build in 7mmRM on a trued early 80's 700 action. I am looking at 9-10 lbs or so final weight with a 26" Broughton or Krieger 1 in 9 twist barrel, utilizing 168 or 180 Berger VLD's or 162 AMAX. I have a couple of questions that I hope someone more experinced in doing these builds can answer:

    Which chamber neck size:
    .311 requiring neck turning
    .315 could use factory ammo if clearance OK
    .318 which I believe is the SAAMI standard

    Which barrel contour?
    I am thinking #5 or #6, preferring #6 (.750 muzzle diameter) although this might make it too heavy. Once built, I will work with it at ranges up to 800 yds but would go to a 1000 on deer sized game if the accuracy is there (and the shooter is capable!)

    Your thoughts would be appreciated.
    Thanks,
    HS
     
  2. Bart B

    Bart B Well-Known Member

    Messages:
    2,483
    Joined:
    Dec 25, 2005
    Get a chamber made to SAAMI specs; no tight neck job. When the 7mm Rem. Mag. was popular for long range prone matches, folks shooting the best scores used that chamber or one a virtual copy thereof. When good, heavy, long match bullets were finally available, they shot sub 3/4 MOA at 1000 yards from both brand new cases as well as properly full length sized ones. The one I used decades ago tested a bit under 2.5 inches at 500 yards with new cases and a special select lot of Sierra Bullets' 168 HPMK's; the only range it was test fired at. When I shot it in a match, the wind was pretty wild. While it held good elevation at 1000 yards, its windage was not anything to write home about.
     

  3. bowhunter42

    bowhunter42 Well-Known Member

    Messages:
    168
    Joined:
    Mar 23, 2011
    We just finished up a new build in 7mm mag. It is wearing a shilen select match #5 sitting in a B&C Medalist with a blue printed older rem700 action, and wearing a Huskemaw 5x20 Blue diamond. the gun weighs 10.2 pounds. we had it out shooting a weekago at 1260 with no problem. If I were you and trying to keep the gun in the 9 to 10 pound range I would not go with the #6 contour, especially if you are gonna be packing it any distance.