Rough Throat?

Discussion in 'Gunsmithing' started by Tumbleweed, Feb 2, 2012.

  1. Tumbleweed

    Tumbleweed Well-Known Member

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    Hi guys, I have somewhere in the neighborhood of 1200 rounds through my 300 RUM. The first 700-800 rounds through it were in a 300Wby chambering. It has never been babied and the loads i've had in it have been on the hot side. I have always kept it clean though. For the last several months I've noticed some noise and a slight rough feel as my cleaning patch moves from the end of the chamber out about 1.5 inches past. As I move away from the chamber the noise goes away and the patch moves down the barrel quietly. To me the obvious conclusion is the that what I am hearing/feeling is throat wear. In your experience is this level of throat wear (assuming that's what it is) excessive to the point of causing inaccuracy issues. My smith looked at it but is old school and does not have a boroscope to take a real good look. He didn't seem to concerned about it after looking down the bore using a mirror and light.
     
  2. Broz

    Broz Well-Known Member

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    In my opinion from past experiences with 300 RUM's. I would order a barrel. You got to be getting close and you will need time to get one, get it on and work up loads before next hunting season.

    Thats what I would do anyway.

    Jeff
     

  3. MTBULLET

    MTBULLET Well-Known Member

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    1200 rounds ? wow, I bet the throat is "shot" (sorry for the pun) my .300 RUM's are only good for 6-800 rds. total. Find a smith with a bore scope and look.
     
  4. Tumbleweed

    Tumbleweed Well-Known Member

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    That is my fear. My next is to let the other smith take a look at it, I believe he's got a boroscope.
     
  5. royinidaho

    royinidaho Writers Guild

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    I'd let the rifle tell me if it wants a new barrel.

    Has velocity dropped of noticeably?
    Has group size gone to pot or at least enlarged noticeably?

    If yes, Tubbs Final Finish has eeked out a bit longer life out of the barrel.

    Either way I'd follow Broz's recommendation. As when they quit it it seems to me they quit all at once....
     
  6. Tumbleweed

    Tumbleweed Well-Known Member

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    Yes, based off of lower poi on target and decreasing normal/typical pressure signs on the case, velocity has dropped with my 210VLD load. Have not chronographed the load for a few months. Have been having some random accuracy issues as well. I originally attributed the accuracy issues to a possible brass concentricity problem or a barrel that was not getting properly cleaned of all copper due to a cleaner issue, but not so sure now. I did manage to get the barrel cleaning issue resolved and it is squeeky clean now. Have been trying to work up a load with the 230 hybrid target with mediocre success at best. I am going to try and shoot a group at 600 yards on Sunday afternoon with the original 210 load and chronograph as well, this should tell the story.
     
  7. Tumbleweed

    Tumbleweed Well-Known Member

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    Well I was able to shoot a 3 shot group Sunday afternoon at 300 yards with my original 210VLD load. I shot it over the chrono and got an average of 3119fps with 7ES and 4SD. The group measured 1.15". I also shot 5 of the 210's in new unfired brass and those averaged 3040fps with around 22ES. They were just as accurate but I was surprised at home much slower the new unfired brass was from the full length sized once fired brass. This explains why my velocities had been low and an absence of pressure signs on the case as I was working on firing the new batch of brass for the first time. I always knew that there would be a difference in velocities between unfired and fireformed brass, just didn't know it could be 80fps. I now believe that my inconsistent irratic accuracy problems had been caused by a barrel that was copper fouled, that problem has been resolved. Rough throat yes, still accurate though!