162-AMAX Problems

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by FRANK21, Jul 2, 2004.

  1. FRANK21

    FRANK21 Well-Known Member

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    Jan 16, 2004
    I have a sweetheart of a custom 7mmRM 28" douglas xx barrel. I have nearly 100 rnds through the barrel. Problem is the 162amax shoots like shit after 2rnds on clean barrel. Like 2" groups.. I didnt spend mucho $$$$ for this. I tried many different powders...to no avail. I bought some 168SMKs to try, and ordered sme Berger 168VLDs. Iguess its something to do w/ fouling. I know Sierras aren't bad about fouling, how are Bergers. What do some of you think.
     
  2. Guest

    Guest Guest

    I'm not to sure that switching bullets is gonna help , if your barrel is so rough that it fouls out after 2 rounds then the barrels is the problem , if your twist rate is correct for those longer bullets

    How does it shoot with say 140gr pills ??

    If the bore is not fouled baddly then it could be a number of things ranging from a loose scope mount to poor bedding , maybe even a "booger" on the crown , could be the barrel is moving some after the first couple shots , is it free floated ? I'd give all those things a once over.

    Now everybody take a DEEP breath and relax

    Assuming that the barrel was broke in and has been cleaned properly , the twist is good 1-10 at least , everything is tight and the only other thing it could be is the barrel , you might want to try fire lapping it , I DO NOT reccomend doing this on custom barrels but it has shown a good improvement in every factory barrel I've ever done.
    BUT
    I'd consult with Douglas and your Smith and see what they are willing to do , I had a custom barrel once that was just bad , the factory replaced it no problem after they checked it out.
     

  3. FRANK21

    FRANK21 Well-Known Member

    Messages:
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    Jan 16, 2004
    thanks guys,

    1. 1-9 twist- crown is a work of art

    2. everything is tight.
    [​IMG]
     
  4. chris matthews

    chris matthews Well-Known Member

    Messages:
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    May 14, 2001
    Tke it to a smith and have him borescope it after a couple of shots. Then have him clean it and borescope it again.
    I'd bet $100 you have a rough bore. A good lapping by a smith or an intense break in is needed.
     
  5. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Jun 12, 2004
    Frank,

    I have seen this quite a bit with A-Max bullet in big cased, high velocity rounds.

    Personally I have witnessed two different rifles that shot the A-Max bullets well up to a certain velocity and then everything went to hell.

    My personal fast twist 30" 6mm-284 shot the 105 gr A-Max bullets into 1/4 moa group out to 500 yards until muzzle velocity got to 3250 fps almost to the number.

    Interestingly enough, at 3225 fps they shot very well. I would have been better off with a long barreled 243 with this velocity range instead of the big volumed 284 case.

    I also found nearly the same to be true with the Berger 105 gr VLD's in that caliber.

    Switching to the 107 gr Sierra Matchkings, I was able to take the 6mm-284 up to 3600 fps with 1/4 moa grouping out to 500 yards.

    THe second rifle was a 7mm RUM that did the same thing, ar right around 3200 fps the accuracy level dropped off dramatically.

    I just feel that the thin jacketed A-Max and the Berger can not handle high velocity, fast twist combinations as the 105 gr 6mm A-Max is designed for 2800-3000 fps of the 243 and 6mm rounds and the 162 7mm bullet is designed for the 7mm-08, 280 and at the largest 7mm Rem Mag rounds.

    I feel your problem is more a bullet integrity failure due to high rotational forces then it is a bore fouling problem.

    As your bore gets hotter, it will get worse as well.

    The shooter using the 162 in the 7mm RUM finally had to go with the 160 gr Accubond and is getting much better results.

    From using the 750 gr A-Max in the 50 BMG, they are much more accurate in the 2550-2650 fps range then if driven faster then that.

    Good Shooting!!!

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