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Posted: 2/4/2005 1:50:07 AM EDT
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OK, I have a new upper that I wanted to break in last Sunday. I take my toys out to the hills and re-zero my scoped upper, then throw the new upper on there. I'd bought a new chromed complete bolt assembly for it. I fire 3-4 rounds, and then CLICK...no fire. Checked the gas rings, no problem there.....???? So I take the bolt from the other upper, and it works fine. The new bolt is identical to my DPMS bolt. As I am relatively new to AR's, I thought I'd ask the Gurus on the board....any ideas / suggestions? Thanks, Justin |
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It failed to eject. I unjammed, then chambered a new round. Went CLICK again. Went I tried to pull back on the charging handle, it was jammed in the closed position. I had to slam the palm of my hand on the latch 3-4 times to get the bolt to get it to go rearward. It was locked up really tight. The ammo is new, quality stuff, have gone through 400 rounds of this same case and never had a problem. Why would it lock up that hard? |
No, I didn't. That this might have been the problem occured to me, but as I'm still learning, and I do not know how to headspace the bolt, or what would be the result of not doing so. How do you properly headspace a bolt? Yeah, I know.....I'm stupid. lol |
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You can't "headspace" a bolt. All you can do is check the headspace of a chamber with a particular bolt. If there is not enough "headspace" then the chamber has to be lengthened with a reamer. And what happens when you don't have enough headspace? Exactly what is happening to you. The bolt slams shut on the cartridge that is too long for the chamber. The cartridge "buckles" under the impact of the bolt, sticking it in the chamber. |
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Always check the headspace before firing with at least a field gauge after having installed a non factory BCG in an upper. Very bad things can happen if you chance it all to blind luck. Proper clearance should be between 1.4646-1.4706, specifically to the .330 in datum diameter of the 1st shoulder of chamber. Kind of technical but important for shooter safety. Hope this helps. |
If this guy has a headspace problem, it's NOT excessive headspace; it's not having enough. Your suggestion is thus useless to him. He needs to have headspace checked w/a MIN guage, not a field guage.  And he's already ID'd the problem. It's an out of spec bolt. He posted that using another bolt worked just fine, so he's already told us where the trouble is. Headspacing will tell him nothing he can't deduce from what he already found out. Send the crappy bolt back, get a refund, and use it to buy a Colt or Bushmaster bolt!!! |
| You might do better reading up and posting in the Troubleshooting Forum. Tweak can give you a definitive word on this probably. |
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