Maximum efficient barrel length??????

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Agunner012, Mar 29, 2006.

  1. Agunner012

    Agunner012 Well-Known Member

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    Thanks in advance,

    I got a good deal on a 7mm 9 twist barrel, now all I need is a stock and a custom 7mm WSM is on deck. For 1000 yard plus target shooting (informal), and occasional LR varmint hunting, what is the longest length I can go without a diminishing return for a 7mm WSM? The barrel is 34" long, and can be finished at 33". I am looking to shoot some of the heavier 7mm bullets.

    Thanks again
     
  2. BountyHunter

    BountyHunter Writers Guild

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    I think you problem will not be in the barrel per say but the action. That long a barrel in a short tenon 700 for instance is not good, wreaks havoc with bedding many times. Plus it will be unweildy as heck.

    Realistically I would think that you will find somewhere between 28-30" would be what works best.

    However, a lot will depend on what contour the barrel is.

    What is the mftr?

    Breach diameter?

    Length of the straight from breach to start of taper?

    Muzzle diameter?

    Blank weight?

    BH
     

  3. Bart B

    Bart B Well-Known Member

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    If it's a cut rifled barrel and thick enough, I'd have it profiled to 1.2 inches at the breech for 5 inches, then a straight taper for 2 or 3 inches down to 1.1 inch, then a long straight taper down to .8 inch at the muzzle. You'll end up with a 33 inch barrel that can be set back one case length after it's worn out and have almost a new barrel again.

    If it's a button rifled barrel, profiling it may change the bore and groove diameters; possibly hurting accuracy.
     
  4. Agunner012

    Agunner012 Well-Known Member

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    However, a lot will depend on what contour the barrel is.

    What is the mftr?

    Breach diameter?

    Length of the straight from breach to start of taper?

    Muzzle diameter?

    Blank weight?

    BH

    [/ QUOTE ]


    It’s a BURX barrel MTU taper is what they called it, at the breech it’s 1.250 tapers down to .930 at the muzzle. Not sure of the exact weight, shipping weight was 10 lbs.

    4 Groove cut rifled barrel. Total time was about 2 weeks to get. They were great guys to do business with. The visual quality is as good as any other custom barrel we have. It will be a while before we build something with it, so a range report is still a while off /ubbthreads/images/graemlins/frown.gif.


    We spec'ed for it to finish at 30" originally, but were plesantly surprised to see the actual length 34". They told us to take the usual 1" off the barrel when finishing it, so we have the option to go to 33" as a finished length.

    Most likely a barrel block would be used, I was wondering what the best length would be for a 7mm WSM, weight not being an issue.

    Again thanks!
     
  5. BountyHunter

    BountyHunter Writers Guild

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    Tapered barrel blocks are very unusual and I would assume difficult to make correctly.

    However, if weight is not an issue, then keep it as long as you can.

    BH
     
  6. Agunner012

    Agunner012 Well-Known Member

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    Thanks BH,

    I have a long barreled 300 RUM 33" barrel, with bedding running I think about 2" in front of the recoil lug, no problems so far.

    I was hoping to go about 30" in length.

    This barrel is a little lighter, so I am guessing if set up the same way it shouldn't be a problem, and would eliminate the block, and problems associated with it.