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tumbling 556

Discussion in 'Ammunition & Reloading' started by tlfreek, Feb 7, 2016.

  1. tlfreek

    tlfreek Vancouver WA Active Member

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    It was a tough day at the range. I found that my bullets are tumbling - the holes in the target are, in some cases, a perfect sideways silhouette of the projectile.

    i am shooting 55 grain hornady fmjbt loaded with 22 grain of LT-32. The cases were necked and sized accordingly. shooting out of an AR which I am unsure of the twist rate. anyone have any ideas on what is causing this? I've shot probably a 1000 rounds out of that gun and have never noticed that. All the prior rounds were mostly my reloads with the remaining being factory ammo.

    Thanks.
     
  2. Certaindeaf

    Certaindeaf SE Portland Well-Known Member

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    What kinda primers are you using?
     
  3. tlfreek

    tlfreek Vancouver WA Active Member

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    cci srp
     
  4. tlfreek

    tlfreek Vancouver WA Active Member

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    i should also add there is a strong crimp on these as well.
     
  5. erudne

    erudne The Pie Matrix PPL Say Sleeping W/Your Rifle Is A bad Thing? Bronze Supporter

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    check your muzzle for build-up 'n burrs
     
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  6. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    I would
    Shoot over a chronograph. Muzzle velocity would be good to know.
    Shoot a box of Hornady factory loads. If they keyhole, it's the gun.
    I note every shot when I work-up a load.
     
  7. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    So was today the first day of using 22gr's of LT-32 in this firearm?

    And also look inside your muzzle break/crown area. I've seen build up that is rather shocking.... Causes all kinds of key holed targets!
     
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  8. tlfreek

    tlfreek Vancouver WA Active Member

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    i see this is a bit more complex than I thought. i've used LT-32 before, the gun was cleaned prior to going to the range. the bullets keyholed or tumbled at both 50 yards and 100 yards. - i dont have a chrono, but may buy one as it seems like the right thing -
     
  9. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    image.jpeg Standard bore cleaning won't remove carbon build up inside the muzzle device and around the crown.. If it even has one.
     
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  10. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    Velzey, great photo!

    Isolate the issue, shoot a box of factory ammo. No stovepiping? It's the reloads.
    My first chronograph was the Chrony F, 35 years old and still works, very basic.
    Current chronograph CED-M2, lots of features and ability to store up to 500 shots.
    Next chronograph will be the MagnetoSpeed Sporter, uses a microsd, downloads to cellphone

    If it's a dirty barrel, brush and mop with Hoppes#9.
    Leave the bore wet with Hoppes, muzzle down, on an old rag.
    3 days later, brush and mop, back on the old rag.
    Notice black and green scum. Black is powder residue, green is copper jacket.
    Do this again and again till the bore is clean. Hoppes works chemically to dissolve the junk.
    Hoppes does not hurt the bore.
     
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  11. Wayne

    Wayne Near Tacoma Active Member

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    Why the crimp ?
     
  12. oli700

    oli700 Rogue Valley Well-Known Member

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    who makes the barrel and is it treated, QPQ, chrome or bare ?

    I have seen sub par barrel steel have rifling shot out in 1000 rounds of hot reloads

    90% of the time it is because the bullet isn't spun up enough.......since you have never seen this before ,the tumbling bullets are light and short it stands to reason the lands are worn in the bore.

    carbon on the crown....doubtful IMO
     
  13. tlfreek

    tlfreek Vancouver WA Active Member

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    stupid lands.
     
  14. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    I've eroded a barrel throat and lands in as little as 300 rounds pushing hot reloads. So it's very possible.
    But when that happens I've never had a keyhole.. Just group growth.
     
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  15. oli700

    oli700 Rogue Valley Well-Known Member

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    I could see a damaged crown but you think carbon would do it ? just doesn't seem like the carbon would exist long enough to contact the bullet more than once
     
  16. Sgt Nambu

    Sgt Nambu Oregon Bronze Supporter Bronze Supporter

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    Get your cleaning rod out and determine your rate of twist.
     
  17. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    I've seen carbon build up so much that I've had to put the barrel in the lathe, go in with a small boring bar and remove it it from the crown and inside the break.
     
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  18. oli700

    oli700 Rogue Valley Well-Known Member

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    should be stamped on the barrel.....but the thing is that it shot fine at one time so twist isn't he problem......

    dang
     
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  19. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    Stupid grooves...
     
  20. tlfreek

    tlfreek Vancouver WA Active Member

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    exactly :)
     
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