1-12 twist for 30-06?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by heelerx2, Nov 6, 2011.

  1. heelerx2

    heelerx2 Well-Known Member

    Messages:
    248
    Joined:
    Feb 7, 2011
    I have a 30-06 built by Penrod. It has a Krieger barrel that is 1-12 twist.
    I am shooting nosler 165 bt. So far I have not been able to shoot less than 1" groups at 100 yards. I was hoping for much tighter groups. My Nosler manual shows 1-10" twist for their test barrel. Will the 1-12 barrel shoot 165's as good as a 1-10?
     
  2. Top Cat

    Top Cat Well-Known Member

    Messages:
    63
    Joined:
    Jul 6, 2005
    Yes...1/12 is in the optimum range for mid-weight 30 cal bullets.

    There are about 100 other variables in rifle and ammo that can affect group size including the bullet itself.

    Try a quick ladder test around your load to find the sweet spot.

    TC
     

  3. Bart B

    Bart B Well-Known Member

    Messages:
    2,483
    Joined:
    Dec 25, 2005
    Over a hundred years ago, the .30-03 shot long, heavy 220 grain round nose bullets. It needed a 1:10 twist at the velocities they left at.

    Three years after its origin, the bullet was changed to a 150 grain spitzer. It only needed a 1:12 twist to stabilize it. But the US Government in all its infinite wisdom decided to keep the 1:10 twist for that new cartridge they called the .30-06 'cause it was thought that would be OK.

    50 years later when Remington designed the 7.62 NATO round, they knew a 1:12 twist was best for the 147-gr. bullet it used. Even though that bullet left about 100 fps slower than the .30-06's 150 grain bullet, it was still very well stabilized. In fact, the 1:;12 twist was better for accuracy. When the 172 grain match bullet was used, accuracy was even better with that slightly heavier bullet.

    But sporting rifles had 1:10 twist barrels 'cause the public thought that was best. They knew the famous M1903-A3 Springfields had it and so did the M1 Garand. So it had to be perfect for the .30-06. But competitive shooters knew that a 168 grain bullet leaving at .30-06 and .308 Win. velocities was the most accurate with a 1:12 twist. A 1:13 twist is the standard for Palma rifles shooting their 145 to 155 grain bullets out at 3000 fps for long range competition.

    So yes, a .30-06 with a 1:12 twist will do just fine with 165's. It may not be fast enough for long, heavy, bullets over 200 grains, but such is life.
     
    Last edited: Nov 7, 2011
  4. heelerx2

    heelerx2 Well-Known Member

    Messages:
    248
    Joined:
    Feb 7, 2011
    Bart B and Top Cat: Thanks for your quick responses. Great info and a piece of mind for me. I'll keep at this rifle till I can figure out what it likes. It has been tough getting the barrel broke in. Still having to soak overnight with Bore Tech to get out the copper after a shooting session.
     
  5. liltank

    liltank Well-Known Member

    Messages:
    4,158
    Joined:
    Nov 3, 2008
    Your barrel break in and cleaning will make it difficult to really find optimum accuracy. I would let the barre l get a little dirty then try your load again. I found the accuracy of my barrel didn't come it until the barrel was completely broke in. It took me around 200-300 rounds for this to happen. Couldn't be happier. I use the 168NBT. Great bullet for the .308 Winny! You may want to try different bullets also.

    Tank
     
  6. rscott5028

    rscott5028 Well-Known Member

    Messages:
    2,608
    Joined:
    Apr 18, 2010
    That sounds excessive. ...especially for a Kreiger.

    I have a Shilen that wasn't breaking in and cleaning up as quickly/easily as I expected. I just completed the Tubbs Final Finish regimine yesterday. It seemed like it was cleaning up easier by the end. But, I'll know more as I start load development with some new components shortly.

    -- richard