Case extraction/chamber issues revisited

Discussion in 'Gunsmithing' started by Freebore, Mar 17, 2009.

  1. Freebore

    Freebore Well-Known Member

    Messages:
    611
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    Oct 23, 2002
    http://www.longrangehunting.com/forums/f37/sticky-chamber-37201/

    I now have close to 300 rounds down the tube of this rifle. Low and behold I tried the regular Norma brass over the weekend and have NO extraction or case hang-up issues. I decided to try them again after going thru 100 nickel I had.

    This a Kreiger chrome-moly barrel. It seems that this barrel has taken close 300 (273) rounds to break-in. It is obvious that I was seeing erratic pressure issues in the beginning and this was what had to be causing the pressure issues. This lead to the case extraction point. I can find no other explaination for this issue.

    Right now I'm at 42.0gr of Varget BR-2 primers 2.800 OAL with a 140 Bal-tip doing 2785 out of a 21" barrel shooting a 3/4" group today. No pressure signs at all but velocity tells me I'm close to max.

    Tomorrow I'm going fishing. Thursday I'll tune the Bal-Tips to <1/2"

    Conversation today with my 'smith was glad to here of the improvement and that he has no explaintion either than that he had heard that cut rifling chrom-moly barrels do take awhile to break in but, that he would not have ever suspected more than 200 rounds. Had my Lghtwght .257 Weatherby do that to me.

    Just thought I'd share with every one the out come of this and my experience with a chrome-moly cut rifling barrel. Thanks to all.
     

  2. LONGSHOOTER

    LONGSHOOTER Well-Known Member

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    Oct 21, 2007
    Freebore,

    You were overloaded.

    Have you tried those old loads again?

    Longshooter
     

  3. Freebore

    Freebore Well-Known Member

    Messages:
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    Oct 23, 2002
    Longshooter,

    Yes, i have tried all of the 'old' loads and they don't work from a grouping point. The velocities were right there as in the old barrel and even much higher with NO extraction issues.

    The reason for the re-post was to inform folks of the amount of rounds this barrel took to break-in.

    The Varget load at 2800fps and no pressure issues (extraction ,primer, or case measurement) does very well. So did the old 760 load just didn't shoot worth a hoot.
     
  4. Spanners

    Spanners Well-Known Member

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    50
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    Dec 1, 2008
    I have found that short barreled 308s prefer powders like H4895, while longer barrels 24+ prefer Varget.
    This was in 20" Rem Tac and Steyr Scouts

    Shoot ok with Varget, but better speed and groups H4895.. burns all the powder in the barrel instead of 1/2 of it over the chrony! :D