Fifty, ? on 300 Allen Express

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by jmden, Dec 29, 2006.

  1. jmden

    jmden Well-Known Member

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    Fifty,

    I apologize if this has been asked before, but what kind of velocities are you expecting to achieve in reasonable pressure loads in the 300 Allen Express based on the 338 Lapua case with the WC 265g and 290g and 30" barrel?

    Sounds like from Jon A's post that the 290g ULDRBBT will need a 1:8.3 to stabilize while a 1:9 will work on the 265g. Sound right?

    Thank you.
     
  2. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Jmden,

    Well, its hard to predict where we will top out at with these bullets as there is no standard to compare them to as the next heaviest bullet used for long range shooting are the 240 and 250 gr pills.

    That said, With that barrel length, I hope to see a bit over 3000 fps with the 265 and 2900 fps with the 290 gr. These are just estimate predictions so its really hard to tell.

    All I have to base these on is that the 7mm AM will hit 3350 fps in a 30" barrel with a 200 gr ULD RBBT and using some comparisions with bore diameter and such these are about what I have come up with. As usual they may be on the conservative side or they may well be to high, not sure yet but will know soon.

    As far as twist rate, I would say Jon A is right on the money. I have a Lawton barrel coming in for testing with a 1-8 LRB rifling design for these bullets in the 300 AX. For the 300 AM, I want to see if the 1-9 will handle everything but thats with alot more velocity output!! Probably 400-500 fps more velocity.

    With same weight bullets, I hope to match what the 30-378 will produce with about 15 grains less powder.

    Time will tell....

    Kirby Allen(50)
     

  3. jmden

    jmden Well-Known Member

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    Thanks, Fifty. That's about what I figured. I'd sure like to have a .308 like that based on the 338 Lapua case.
     
  4. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I know where you can get one here soon /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

    Kirby Allen(50)