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Posted: 11/17/2013 2:57:45 PM EDT
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Okay guys, I am a noob here. I have looked around the internet, and these forums and have found some answers I think help me with my problem, but nothing that's exactly like mine.
I have built two AR-15's to the same spec. I have a Ares Arm lower, Cmmg lower parts kit, Rock River Arm upper, Vltor stock and tube/buffer kit, Ice Arms bolt carrier group, 16" .223 Wylde Bergara Barrel with 1.9 twist, yank hill quad rail, a generic gas block/tube and generic flash hinder. I have been shooting cheap 55 grain fmj Remington's that run $15 a box. Okay all my specs aside, my problem lies in that when I shoot every once in a blue moon the bolt wont cycle all the way and will jam the gun. Last night when I finished my builds I went out to the range and ran 20 bullets just fine with out a single hitch. My dad also shot the other AR without a problem himself. Today we went out, same range, same bullets, same everything. We shot 20 round each and we had 3 jams each. I noticed when I watched my dad shoot that his bolt wouldn't fully cycle when it jammed So this leads me to believe three things. Either I messed up with my gas block and tube on both guns, since both jammed 3 times today. 2 The spring/buffer to are to strong for the bolt to over come and thus are preventing them from cycling which wouldn't make sense since they shoot great the rest of the time. Or thirdly, and my biggest suspect so far, is the ammo is bad. Either a low charge or something, and so the bolt isn't getting a full charge and is thus having a problem cycling all the way back. I figure I will get better ammo, work my way up the list of suspect problems and see what fixes it. However I was wondering if you experts out here could tell me what you think my problem is? I feel everything I got part wise like the bolt and upper are good parts so I'm not to sure if they would be causing my bolt to not fully cycle. I don't know AR's are new to me. Eventually I will be hand loading my .223 rounds and I won't have to worry about cheap bullets fouling things up. |
You're on the right track to suspect ammunition. In general, 223 ammo is loaded to a lower pressure than 5.56, so that change may be all that's needed. It won't hurt to thoroughly clean the chamber with a chamber brush and CLP, and run the bolt wet. You want to eliminate any unnecessary friction that could be slowing the bolt/carrier. If it continues to malfunction after those steps, then you can suspect the gas system. 
HTH GSM |
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Swap out the B/C's of the two rifle, and see if the problem transfers to the other rifle. If no, then swap the uppers and try again. Here you want to weed out not only the B/C's but the lower as well.
If no, then it could be a cleaning/lubing problem of the upper in question, or as you noted, the gas block not correctly aligned/gas tube alignment, or even the key binding in the upper receiver causing the weak strokes. Lastly, get some factory brass case ammo to break in the rifles. When new, the anodized parts do bind up against the parkerized parts, and most of the time, take full strength brass ammo to allow the rifle to self polish the parts in. |
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Quoted:
You're on the right track to suspect ammunition. In general, 223 ammo is loaded to a lower pressure than 5.56, so that change may be all that's needed. It won't hurt to thoroughly clean the chamber with a chamber brush and CLP, and run the bolt wet. You want to eliminate any unnecessary friction that could be slowing the bolt/carrier. If it continues to malfunction after those steps, then you can suspect the gas system.
HTH GSM Thanks for the input, glad to hear I am on the right track here :) It's a rare case, everyone either has no cycle or it does but never hits the bolt catch. However mine run perfectly smooth except once in a blue moon it cycles short. When I torqued the barrel nut down I was OCD about making sure the gas tube fit right and checked that everything lined up with the bolt catch. I also don't see any fouling around the gas block to suggest that it's leaking. Anywho, better rounds first. Would you have any tips on how I can make sure my gas block is line up correctly if the new rounds don't fix anything? I am just curious, always good to know in case/when I make more on how to do it :D Quoted:
Swap out the B/C's of the two rifle, and see if the problem transfers to the other rifle. If no, then swap the uppers and try again. Here you want to weed out not only the B/C's but the lower as well. If no, then it could be a cleaning/lubing problem of the upper in question, or as you noted, the gas block not correctly aligned/gas tube alignment, or even the key binding in the upper receiver causing the weak strokes. Lastly, get some factory brass case ammo to break in the rifles. When new, the anodized parts do bind up against the parkerized parts, and most of the time, take full strength brass ammo to allow the rifle to self polish the parts in. I have a friend with a AR-15, mayhaps we could swap bolts one day at the range and see how that works. I have recently lubed them up pretty good. I was running them on the rather dry side, so next time that will be taken out of the equation, but again I'll be using different brands of ammo so I'll never know what truly fixed it, if it does indeed stops. |
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Quoted:
Thanks for the input, glad to hear I am on the right track here :) It's a rare case, everyone either has no cycle or it does but never hits the bolt catch. However mine run perfectly smooth except once in a blue moon it cycles short. When I torqued the barrel nut down I was OCD about making sure the gas tube fit right and checked that everything lined up with the bolt catch. I also don't see any fouling around the gas block to suggest that it's leaking. Anywho, better rounds first. Would you have any tips on how I can make sure my gas block is line up correctly if the new rounds don't fix anything? I am just curious, always good to know in case/when I make more on how to do it :D <snip> I have a friend with a AR-15, mayhaps we could swap bolts one day at the range and see how that works. I have recently lubed them up pretty good. I was running them on the rather dry side, so next time that will be taken out of the equation, but again I'll be using different brands of ammo so I'll never know what truly fixed it, if it does indeed stops. Quoted:
Quoted:
You're on the right track to suspect ammunition. In general, 223 ammo is loaded to a lower pressure than 5.56, so that change may be all that's needed. It won't hurt to thoroughly clean the chamber with a chamber brush and CLP, and run the bolt wet. You want to eliminate any unnecessary friction that could be slowing the bolt/carrier. If it continues to malfunction after those steps, then you can suspect the gas system.
HTH GSM Thanks for the input, glad to hear I am on the right track here :) It's a rare case, everyone either has no cycle or it does but never hits the bolt catch. However mine run perfectly smooth except once in a blue moon it cycles short. When I torqued the barrel nut down I was OCD about making sure the gas tube fit right and checked that everything lined up with the bolt catch. I also don't see any fouling around the gas block to suggest that it's leaking. Anywho, better rounds first. Would you have any tips on how I can make sure my gas block is line up correctly if the new rounds don't fix anything? I am just curious, always good to know in case/when I make more on how to do it :D <snip> I have a friend with a AR-15, mayhaps we could swap bolts one day at the range and see how that works. I have recently lubed them up pretty good. I was running them on the rather dry side, so next time that will be taken out of the equation, but again I'll be using different brands of ammo so I'll never know what truly fixed it, if it does indeed stops. Just place the GB against the barrel shoulder, and eyeball it centered within the hand guard. The GB's port is larger than the port in the barrel, so they're somewhat tolerant of misalignment. HTH GSM |
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