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-   -   Bolt/Magazine problems (http://www.firearmstalk.com/forums/f20/bolt-magazine-problems-80713/)

JonnyV 01-08-2013 08:02 PM

Bolt/Magazine problems
 
I've only had my freshly built AR to the range twice but each time I was having issues with rounds feeding into the chamber. Seems the bolt is just skimming over top the rounds. However, I can use the charging handle to rack them in. But then the case is ejected and the bolt skims over the next round resulting in that ever so disappointing "click". It go to the point where I could feel and hear a difference. On a few rare occasions it fed just fine. Should I be looking into a different mag? I'm just using a steel 20rd Bushmaster mag right now.

JonM 01-08-2013 08:07 PM

Prolly an issue with the gas system not letting enough gas through to fully cycle the bolt or a too heavy recoil spring or buffer or combination of those.

If it doesnt lock the bolt back with an empty mag your not getting enough energy to get the bolt rearward. Doesnt sound like a magazine issue

Saw this happen once when someone crammed a rifle length spring into a carbine buffer tube.

JonnyV 01-08-2013 08:19 PM

Quote:

Originally Posted by JonM (Post 1085387)
Prolly an issue with the gas system not letting enough gas through to fully cycle the bolt or a too heavy recoil spring or buffer or combination of those.

If it doesnt lock the bolt back with an empty mag your not getting enough energy to get the bolt rearward. Doesnt sound like a magazine issue

Saw this happen once when someone crammed a rifle length spring into a carbine buffer tube.

Interesting. I did notice that the bolt seemed to be locking over the magazine after the last round instead of at the bolt catch behind the mag. I'll have to have this looked at.

robocop10mm 01-08-2013 09:17 PM

I am betting on short cycling. Gas pressure, volume, bolt carrier group weight, buffer weight and buffer spring must me in "harmony".

JonnyV 01-14-2013 02:08 PM

Alright, got a day off and decided to look into this issue. The suggestions about gas pressure/volume got me thinking. My DPMS bull barrel came with a gas block with a pic rail, it wouldn't fit under my handguard so I swapped it out. I noticed the set screws didn't line up with the divots on the barrel perfectly, but close...not close enough. When I pulled the handguard off I saw powder residue forward of the block, it was coming out from underneath it. I'm in the process of modifying the original to fit, just a little careful time with a grinder. We'll see if this works. If not, I'll look into the buffer and spring. Thanks for the help so far guys.

Quentin 01-14-2013 02:19 PM

Yeah sounds like you're on the right trail now. The ground down original should seal properly and solve the short stroking issue.


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