1 in 12" twist in 300 Ultramag

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Rodbolt, Mar 2, 2007.

  1. Rodbolt

    Rodbolt Member

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    1 in 12\" twist in 300 Ultramag

    I purchased a 1999 Montana barreled action off Gunbroker in 300UM and bedded it in Accurate Innovations stock. After working up my best loads with the 200 AB (RL-25 @ 3225fps) accuracy was not what I expected at 100 yards (just over an inch) but it I'm getting decent (~ 2", several under) groups at 330 yards which I used to sight in for an elk hunt last fall. I've not shot it at long range but ended up using my .338 WM for the hunt.

    I measured the twist with a tight fitting patch and was surprised it showed 1 turn in 12.3" !! I have little interest in a lighter bullet but most barrel makers show a 1 in 10" is needed for 200 grain bullets. I appreciate any input or ideas on this.
     
  2. demarpaint

    demarpaint Well-Known Member

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    Re: 1 in 12\" twist in 300 Ultramag

    10 twist is ideal, 11 should work, 12.3 probably not. Try a 175 SMK or a 168 maybe.

    FD
     

  3. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Re: 1 in 12\" twist in 300 Ultramag

    I would use the 180 gr Accubond if you like the performance of the 200 gr version on game. You loose a bit of BC but gain velocity as well and very similiar on game performance.

    Not knocking the MRC receiver but it is not known for tack driving consistancy.

    Kirby Allen(50)
     
  4. POP

    POP Well-Known Member

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    Re: 1 in 12\" twist in 300 Ultramag

    That is not all that bad. 2 inch groups at 330 yards translates to .62 MOA. Not too shabby.
     
  5. James Jones

    James Jones Well-Known Member

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    Re: 1 in 12\" twist in 300 Ultramag

    I'd personaly try the 180 accubonds like Kirby mentioned they will work a little bit better with that twist and out to 600yds the game will never no the differance and I doubt that the drop would be very differant between the 200 and 180 accubonds
     
  6. Rodbolt

    Rodbolt Member

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    Re: 1 in 12\" twist in 300 Ultramag

    Thank you for the tips. It does make sense to try the lighter bullets or a shorter profile. I'll order the 180's and borrow a few 175's for a test. I know the MRC doesn't have a stong following but this barrel (stainless fluted) quit coppering early and is easy to clean, relative to the amount of powder consumed, I hate to give it up. The action was not well finished, gritty, but responded to some tlc.
     
  7. Michael Eichele

    Michael Eichele Well-Known Member

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    Re: 1 in 12\" twist in 300 Ultramag

    I do get great resuls with the 200 AB in a 12x Lilja barrel. I have shot these loads out to 650 yards to date. In cold dense sea level air, they are stable at 650 yards. Accuracy with my best loads is about .3 MOA Velocity is 3147 FPS out of the 300 RUM. 12x is very slow for the 200 AB. 12.3 would be borderline unstable, but if youre getting them to stabilize, you dont need to worry. I also agree with others here about the 180 AB. My 300 12x likes them a bit better in the accuracy department.

    Welcome!
     
  8. davewilson

    davewilson Well-Known Member

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    Re: 1 in 12\" twist in 300 Ultramag

    i'm with POP on this one. you're getting 2" and under at 330 yds with a big game hunting gun.what level of accuracy are you looking for? if you're looking for better than that,sell the Montana and get a Lawton.

    i would also agree if the 180's shot better, i'd go with them because the terminal performance difference would be measured in BFD units.