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Posted: 7/5/2012 4:31:26 PM EDT
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I had posted here before about my PSA upper and the ejector problems I had or should I say the problems that began. I purchased the upper sometime last year and didn't get a chance to shoot it until I moved.to Mississippi. Fast forward to now and I solved the ejector problem but it still stovepipes and double feeds even after a new bolt. On different lowers, different mags, different ammo etc. I can not figure it out to save my life.
Only thing i havent tried is a different bolt carrier or a fixed stock lower. Without fail now 8-10 rounds into a string of fire slow or rapid it does it. Any ideas? Chamber need reaming? I am out of ideas. ETA; Just read a few posts of similar problems... Will try to swap bolt carriers since the upper still won't stop doing it on two different lowers. Will look at the length of the bolt carrier vs. Another and try the quarter in the extension trick to see if that is it. Any other ideas? Posted Via AR15.Com Mobile |
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Quoted:
what is your gas tube length/barrel length? Is your buffer tube a rifle length tube or a carbine six position one? what ammo are you using? Sorry my bad its a PSA 16" CARBINE HF upper, regular weight carbine buffer in a PSA lower kit CARBINE extension tube. Ammo is American eagle brass case 55 gr and Federal M855 62 gr. Mags are aluminum both with black followers and magpul. Tried another lower M&P with factory CARBINE tube as well with a H2 buffer. Posted Via AR15.Com Mobile |
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Inspected BCG's from all of the AR's I have and they are identical in length. Will try to swap out Bolt Carriers tomorrow and put in a spacer in the tube to see if that helps.
I am using a semi auto carrier if that matters, it has not in all the other AR 15's I fired. |
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Lets start off at the top,
Does the bolt lock back on the bolt catch (catch in front of the bolt, and not just grabbing the bottom of the carrier) if you only load one round into a mag, charge and fire that round with the empty mag still in the rifle? When you pull the charging handle all the way back, does the face/front of the bolt stop about 1/4" to 3/8" in front of the back of the ejection port window? With the bolt alone in hand, when you hook a spent case on the extractor and cam the ejector into the bolt face a few times, is the ejector binding in the bolt face channel. On the extractor, add a #60 O ring (about a dime at any hardware store) around the outside of the extractor spring before reinstalling the extractor. The increased tension of the extractor spring will weed of if the spent case is being dropped before the end of stroke. Lastly, when you say double feed, if two live rounds, then the mags at hand are total crap. Double live round feeds only come from bad mags alone. The stove piping, that is what the above is all about to see where the problem lies. |
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Quoted:
When you pull the charging handle all the way back, does the face/front of the bolt stop about 1/4" to 3/8" in front of the back of the ejection port window? Can you please point out where in the TM9 it says this is a spec? I cannot find it anywhere in there. |
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Quoted:
Lets start off at the top, Does the bolt lock back on the bolt catch (catch in front of the bolt, and not just grabbing the bottom of the carrier) if you only load one round into a mag, charge and fire that round with the empty mag still in the rifle? I did not look for this I will check today. When you pull the charging handle all the way back, does the face/front of the bolt stop about 1/4" to 3/8" in front of the back of the ejection port window? My other carbines bolt face goes back further than this one and has no issues With the bolt alone in hand, when you hook a spent case on the extractor and cam the ejector into the bolt face a few times, is the ejector binding in the bolt face channel. Both the old and new bolt work fine On the extractor, add a #60 O ring (about a dime at any hardware store) around the outside of the extractor spring before reinstalling the extractor. The increased tension of the extractor spring will weed of if the spent case is being dropped before the end of stroke. I have the Crane O ring and a stronger spring on the older bolt that I rebuilt have not checked the new one but I doubt it would matter on a function check with a spent case they both seem to have no hangups. It ejects strong when it does not stove pipe. Lastly, when you say double feed, if two live rounds, then the mags at hand are total crap. Double live round feeds only come from bad mags alone. The stove piping, that is what the above is all about to see where the problem lies. Its stove piping sorry for the confusion and my mags run fine in my other guns Checklist of trouble shooting I will conduct today until I figure it out or run out of ideas I will be using 55gr american eagle, aluminum GI mags both with magpul and regular followers (which are flawless in my other guns) and some new to me Hk steel maritime mags; Check bolt catch. Replace bolt carrier with another. If the bolt catch is somehow the problem this may solve it. Use a rifle lower to check out if a heavy buffer is the answer if it is replace carbine buffer with 9mm or H3. Use a rifle lower and a swapped bolt carrier. Rebuild new bolt with O ring and new spring (my old bolt has this and it did not help) Put a spacer in the bottom of the buffer tube to make the bolt show its self in the ejection port. If all else fails I will have to take it to a smith or see if PSA will take it back and trouble shoot it or replace it. |
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All you need it a handful of quarters.
Pull the buffer and buffer spring, and start stacking quarters down the tube (between it and the end of spring) until when you go to pull everything back together, the face of the bolt stops about 1/4" in front of the back of the ejection port. Simply, with the face of the bolt retracting back past the back edge of the port window, when the spent case goes to pivot off the bolt face at rear stall, the case is being defected off the back of the ejection port window and back in the action. |
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Range Report;
Went to the indoor local range to see if I could figure it out. I started firing to see if I could get it to malfunction. My buddy and I put over 300 rounds downrange with only two stovepipes in the middle of the firing and two magazine induced malfunctions (magazine follower got stuck and tilted). I dont know what the hell happened it ran like a piece of crap just the other day and now today only two stovepipes and two other malfunctions! We fed it everything from 55gr American Eagle, 50gr American Eagle, 55gr Federal, 55gr Tula steel case and 62gr OTM. We used GI issue magazines, GI mags with magpul followers, Hk Steel Maritime mags, Pmags, and even a unknown plastic mag. We tried to get it to fail by not lubing it at all wiped it down to dry on the inside, shot several strings of sustained rate fire until the barrel was smoking. I even swapped the lower out to my rifle lower and then back to the carbine lower. It ran fine except for the above mentioned malfunctions. I am at a loss what would make a AR run like a turd and then it comes back and runs like a swiss watch. |
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Sounds to me like the gun might be marginally undergassed, and intermittently short stroking.
causes could be a gas leak at the front sight or on the bolt carrer. It's normal to have a slight gas leak at the front sight on a brand new barrel. This seems to seal up with rounds sent downrange. You could also be having a leak due to a loose carrier key on the bolt carrier. Other uppers with larger gas ports might not experience the same problem/s. I'd try a different BCG. |
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