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Thread: 243 barrel length

  1. #1

    243 barrel length

    Hi

    I have a 243 sako 75 that im thinking of chopping the barrel to 20" to match my 85 308. Is this feasible for a 243 and what difference in ballistics could I expect

    ATB Steve

  2. #2
    Hi I copied the following from the chuck hawkes website very intresting info should be of help



    Other authorities have tried to take into account the different velocity ranges within which modern cartridges operate. The Remington Catalog 2003 includes a "Centerfire Rifle Velocity Vs. Barrel Length" table that shows the following velocity changes for barrels shorter or longer than the test barrel length:
    • MV 2000-2500 fps, the approximate change in MV per 1" change in barrel length is 10 fps.
      MV 2500-3000 fps, the approximate change in MV per 1" change in barrel length is 20 fps.
      MV 3000-3500 fps, the approximate change in MV per 1" change in barrel length is 30 fps.
      MV 3500-4000 fps, the approximate change in MV per 1" change in barrel length is 40 fps.
    The 45th Edition of the Lyman Reloading Handbook also has a table showing Center Fire Rifle Velocity Vs. Barrel Length. Their figures apply to barrels between 20 and 26 inches in length and agree with the Remington figures. The Lyman table shows the following approximate velocity changes:
    • For rifles with muzzle velocities in the 1000-2000 fps range, the change in velocity for each 1" change in barrel length is 5 fps.
      For rifles with muzzle velocities in the 2001-2500 fps range, the change in velocity for each 1" change in barrel length is 10 fps.
      For rifles with muzzle velocities in the 2501-3000 fps range, the change in velocity for each 1" change in barrel length is 20 fps.
      For rifles with muzzle velocities in the 3001-3500 fps range, the change in velocity for each 1" change in barrel length is 30 fps.
      For rifles with muzzle velocities in the 3501-4000 fps range, the change in velocity for each 1" change in barrel length is 40 fps.
    The 43rd edition of the Lyman reloading Handbook gave some concrete examples of velocity loss for specific calibers and loads. The Lyman technicians chronographed some high velocity cartridges in rifles with barrels ranging in length from 26 inches down to 22 inches with the following results:
    • The average loss for the .243 Win./100 grain bullet was 29 fps per inch.
      The average loss for the .264 Win. Mag./140 grain bullet was 32 fps per inch.
      The average loss for the .300 H&H Mag./220 grain bullet was 25 fps per inch.
    For standard high intensity cartridges in the same test, the Lyman technicians chronographed the cartridges in barrel lengths ranging in length from 24 inches down to 20 inches with the following results:
    • The average loss for the .270 Win./130 grain bullet was 37 fps per inch.
      The average loss for the .270 Win./150 grain bullet was 32 fps per inch.
      The average loss for the .300 Sav./180 grain bullet was 17 fps per inch.
      The average loss for the .30-06/180 grain bullet was 15 fps per inch.
      The average loss for the .35 Rem./200 grain bullet was 11 fps per inch.
    After a bunch of disclaimers, the Lyman people concluded, "The rule of thumb is that high speed, high pressure cartridges shed more speed in short barrels than do the low speed, large bore types." It's funny, but that is what I had suspected all along!

  3. #3
    I worked out with my 20" barrel i had lost around 50 fps per inch of barrel cut off using the slower burning powders.

  4. #4
    were using them as short as 16" with out probs ..

  5. #5
    irishgun what velocities ad muzzle energies are you getting?

  6. #6
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    Quote Originally Posted by Bordersman View Post
    Hi

    I have a 243 sako 75 that im thinking of chopping the barrel to 20" to match my 85 308. Is this feasible for a 243 and what difference in ballistics could I expect

    ATB Steve
    As already posted: 20-50 fps lost per inch chopped off. 20" should therefore be OK. Shorter could be a problem. You don't say what you'll be shooting or where you go to shoot.

    Small deer and Scottish Roe you'll be fine.

    but.... for ALL deer in England, for instance, you need an M.V. of at least 2767fps with a 100grain bullet to get your 1700ftlbs minimum M.E. as required. In Scotland, where you must use at least a 100 grain bullet for ALL deer and attain a minimum M.E. of 1750ftlbs, you need to chase that same pill out the pipe at no less than 2807.5fps. Can a 16" bbl, chambered to .243win, actually do that last one with normal factory ammo???

  7. #7
    Surely only 1000 ft lbs for roe in Scotland, with the 1750 ft lbs requirement applying to fallow, red and sika?

  8. #8
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    Quote Originally Posted by RoyalTW View Post
    Surely only 1000 ft lbs for roe in Scotland, with the 1750 ft lbs requirement applying to fallow, red and sika?
    Sorry Royaltw, if you misunderstood... There's "small deer" and "all deer" regulations. Re-read my post and you'll see I said there'd be no problem on Scottish Roe.

    ps. You can shoot Roe with cartridges which perform in the "all deer" class, most folk do.

  9. #9

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