AR Sponsor
Posted: 1/19/2016 5:19:52 PM EDT
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I finished my AR15 5.56 build last week. I checked the headspace with my go nogo gauges and it passes. I got to the range and when I went to chamber the first round, it wouldn't close 100% so I removed the round and tried to chamber the 2nd round. This time the bolt jammed shut. I had to wait until I got home and was able to use a piece of wood and hammer on the charging handle to unjam the bolt.
I've removed the barrel and reinstalled it again and also checked the bolt. Everything looks correct. This issue only happens when I try to chamber a round. The bolt will seat 100% when the chamber is empty. Any ideas? |
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What ammo, and if reloads, has it been put through an ammo case gauge to make sure it was fully resized even after loading?
Have you pull the bolt off the carrier and used just carrier with key in the upper receiver to confirm that the gas tube is correctly aligned with the key? What charging handle in play and if the bottom front tab of the CH handle too long and binding on the top of the carrier? Extractor, are you using a O ring around the extractor spring that may need to be removed, and have you checked the rim releif channel on the extractor to make sure it correctly placed and the extractor can fully seat home once the round had snapped on to the bolt face/ the extractor. Lastly, have you check the FA to make sure that the pawl is fully retracting back into the channel, and not binding up on the side of the carrier isntead. As for the bolt and the barrel extension, they do need to mate in a touch, so if all the above checks out, may take a few live rounds for the rear barrel lugs and the inside of the barrel extension lugs to self polish out/ knock off any milling burs. So on the load, make sure that you are not riding the charging handle back foward, then ammo is good, the chamber is scrubbed clean with a chamber brush and CLP by hand, the upper receiver bearing areas lubed correctly with CLP, and shot the rifle for a mag or two to see if such is still a problem. |
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Here's the latest..
Purchased a box of factory ammo and bolt closes on all of them without any issue. So it's not the rifle. It looks like when I adjusted the die for my LNL, the die was adjusted enough to full length resize the die, but not enough to push back the shoulder enough to factory spec. The die has been readjusted and created a few dummie rounds that chamber correctly. I've already placed an order for a case guage for future use. 20 years of reloading and my 3rd AR build and still learning. A big thank you for the help. The ideas definitely pointed me in the correct direction. |
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Quoted:
Here's the latest.. Purchased a box of factory ammo and bolt closes on all of them without any issue. So it's not the rifle. It looks like when I adjusted the die for my LNL, the die was adjusted enough to full length resize the die, but not enough to push back the shoulder enough to factory spec. The die has been readjusted and created a few dummie rounds that chamber correctly. I've already placed an order for a case guage for future use. 20 years of reloading and my 3rd AR build and still learning. A big thank you for the help. The ideas definitely pointed me in the correct direction. Buy a case gauge to check to make sure that you are not only, full sizing the case to begin with, but that you are not over pressure bullet crimping to cause the case shoulders to bulge as well; with the cases not longer correctly full sized when the ammo is fully loaded. Also, the case gauge comes in handy to make sure that you have correctly trim lenght the cases when they are batch trimmed as well. http://www.stu-offroad.com/firearms/reloading/casegauge/casegauge-1.htm Lastly, not sure that you are using to bullet crimp, but if you are using a combo bullet seat/crimper die, then use that die to only bullet seat, then get a Lee FCD to bullet crimp. The Lee FCD does not rely on the cases all be unformed trimmed to length to is applies the same bullet crimp pressue to all the rounds put through it, and have no fear of bulging the case shoulders with the Lee FCD. |
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