Page 2 of 5 FirstFirst 1234 ... LastLast
Results 11 to 20 of 41

Thread: Barrel worn out?

  1. #11
    Join Date
    Jul 2009
    Posts
    2,177
    Feedback Score
    13 (100%)
    1. Try the possibly bad ammo in another rifle, preferably as similar to yours as possible, and see how it performs.

    2. Check the crown and the headspace of your existing barrel.

  2. #12
    Join Date
    Oct 2011
    Location
    Alaska
    Posts
    3,523
    Feedback Score
    3 (100%)
    That's two folks that have suggested head space. I know that headspace issues can crop up with really long term rifle use, but wouldn't throat erosion occur LONG before that. In conversations with IG and a couple other armorers, they had very few occurrences of rifles having headspace issue before the barrel was worn out. What is worn out headspace? It's got to be totally hosed to not pass a field guage, and very few people have access to a set of guages to measure actual headspace.

    I'm betting it's ammo related.

  3. #13
    Join Date
    Jul 2006
    Posts
    2,207
    Feedback Score
    7 (100%)
    I'd be very, very surprised if headspace-due-to-round-count was the issue. I've sectioned several barrels with 20K plus through them and you can still see toolmarks on the shoulder of the chamber. Which is not to say the barrel extension and bolt could not have worn / stretched, but in these cases they had not.

    It's the same thing that gets every barrel-- the throat. Some ammo will be more sensitive to it that others.

  4. #14
    Join Date
    Jan 2008
    Location
    AZ-Waging jihad against crappy AR's.
    Posts
    24,902
    Feedback Score
    104 (100%)
    Same thing I was thinking. Either the throat is worn out, or the ammo is bad. I would definitely run it in another AR to be sure.

    Quote Originally Posted by Ned Christiansen View Post
    I'd be very, very surprised if headspace-due-to-round-count was the issue. I've sectioned several barrels with 20K plus through them and you can still see toolmarks on the shoulder of the chamber. Which is not to say the barrel extension and bolt could not have worn / stretched, but in these cases they had not.

    It's the same thing that gets every barrel-- the throat. Some ammo will be more sensitive to it that others.



    Owner/Instructor at Semper Paratus Arms

    Facebook: https://www.facebook.com/SemperParatusArms/

    Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/

    M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141

    Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com

  5. #15
    Join Date
    Oct 2007
    Location
    Back Home in TEXAS where I belong!!!
    Posts
    293
    Feedback Score
    8 (100%)

    Barrel worn out?

    I had14,000+- a few hundred through my S&W 1/9 twist barrel before I replaced it. It would shoot 3-4" group all day with 55gr ammmo till it hit about 12,000 rounds then it opened up to over 6". I finally broke down and replaced it with a Rainer arms select barrel. Now it shoots 2" and under all day with 55gr and under 1" with BH 75gr match.

  6. #16
    Join Date
    Jul 2012
    Posts
    39
    Feedback Score
    0
    At 6,500 rounds, the barrel may not be worn out, yet there may be a combination of Throat Erosion, and Bolt Lug wear to decrease the accuracy of the shorter 55gr projectile... As some have stated not everyone has Head Space Gauges, or Calipers to check the Bolt Lugs...
    As the round is fired in the chamber, the Bolt will get pressed back from the pressure, if the Lugs have some wear, in conjunction with Throat erosion, this could cause poor accuracy with the shorter 55gr projectiles, yet not with the slower less pressure, and longer 69 gr match loads...

  7. #17
    Join Date
    Jan 2007
    Location
    Charlotte, NC
    Posts
    163
    Feedback Score
    23 (100%)
    At this point, if it can be deemed that the throat is indeed the issue, I would compare the cost of replacing the barrel versus selling the 55gr and using heavier loads for the foreseeable future. Given the current ammo situation, it may be more cost effective to replace the barrel.

  8. #18
    Join Date
    May 2011
    Posts
    8
    Feedback Score
    0

    Thanks for all the info---

    New 16" barrel and BCG on the way--it was faster than leaving the rifle with the shop, and cheaper than buying more high grade ammo. I'll zero the new barrel with match grade 69grn and try out the 55grn XM193 again. Then the old barrel and BCG will go to the gunsmith for evaluation.

  9. #19
    Join Date
    Jul 2006
    Posts
    2,207
    Feedback Score
    7 (100%)
    Using the ammo it still shoots well, it's gonna at some point go bad like all at once, that is, over a 200-round stretch.... that's my prediction. Not gonna say which 200 rounds...... that would be risky.. Speaking of chamber throats wearing and causing accuracy issues, I......

    <<static sound>>
    We interrupt our regular program to pass on this little tidbit from my days with a guy I apprenticed with, who was a benchrest legend (Robert Simonson). A barrel that had proved itself a good grouper, he would shoot it a season or two, and could notice accuracy dropping off (like, 100-yard groups "opening up" to .290"). At that point he would remove it, and sometimes set it back a certain distance (I don't remember, I didn't say I was a good apprentice, but I'd say maybe 1/2"), but sometimes he would cut the chamber end off, crown it, and then thread and chamber the other end! Mind you these were barrels that were uncontoured and untapered-- the outer diameter was the way it was when it came as a blank-- like, 1 1/4" diameter-- they maybe had a light turn to make it concentric to the bore. These were "rail guns": a barrel, an action, a custom-made machine rest and a couple dial indicators.

  10. #20
    Join Date
    Apr 2009
    Location
    Dallas, TX
    Posts
    2,347
    Feedback Score
    2 (100%)
    Quote Originally Posted by Ned Christiansen View Post
    sometimes he would cut the chamber end off, crown it, and then thread and chamber the other end!
    Simply awesome

Page 2 of 5 FirstFirst 1234 ... LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •