AR Sponsor
Posted: 8/22/2011 2:52:55 PM EDT
|
I just installed a new Palmetto state Armory 16" Hammer Forged complete upper with 1-7 twist. I sighted the upper in tonight but the bolt refuses to lock open following the last round.
I am using my Bushmaster XM-E2S and the original 1-9 twist A1 heavy profile carbine works great. I conducted several loading drills with both uppers and the Palmetto refuses to lock open following the last shot round. I've even switched out the magazines using different magazines and the same would occur with the Palmetto bolt not locking back. Ammo used: PMC X-Tac, 5.56 NATO 62 gr Green Tip -Lap. Is anyone else having the same problem with Palmetto’s uppers? This ammo shot fabulously in my original Bushmaster 1-9 Heavy Carbine with A1 sights. I'm beginning to enjoy A1 sights much more these days. Easy to adjust and just leave it. I've has A2 sights elevation knobs move through fast handling in an out of case. |
|
like to also add.. what type of buffer tube you running??
I'm running my standard DPMS lower Carbine Buffer/Spring that came with my lower and the SAME ammo.. my PSA is ejecting 1-2 o'clock..(rumor is Armalite seeks 1-2:30 ejection) but with over 1000 rounds without issues it doesn't matter to me.. Can you insert an EMPTY mag pull the charging handle and have it stick?? check the lower bolt-catch.. just tossing ideas.. |
| Not sure what type of buffer is in my Bushmaster Carbine. It is a pre-ban rifle I had purchased years ago and decided to put it to use as a duty/patrol rifle. I can't have this upper failing when called upon. What would the buffer have to do with the upper not locking back? Other than that it cycles fine with a variety of magazines. I have a Matech BUIS on the Palmetto upper and I'm having extreme problems zeroing my rifle with the 62 gr. ammo. At 50 yards my front sight post is almost bottomed out and my rear elevation knob has to be on the 600 yard mark in order for me to hit dead center of aiming point on the target. I must be doing something wrong or I'm not using the correct ammo, puzzling…. PAT. |
it runs FINE with a variety of magazines.. but your bolt does not lock back on the last round 
the mags run fine when firing.. but not after the last round.. the buffer may be to light/heavy to properly cycle with the new upper.. hence a short stroke or long stroke and the lack of lock-open.. have you tried pulling the CH back on an EMPTY MAG and see if it stays open?? maybe the BOLT-CATCH is an issue on the lower?? FWIW.. your not the only person with issues with the MATECH rear sight FWIW.. Your Palmetto FSB is F marked height which may be causing you to be off.. you may need a longer POST.. others should be along to chime in.. try the EMPTY MAG idea and report back your findings with the different mags.. |
|
Quoted:
sounds like short stroking to me. could be an ammo related issue or gas system issue. what ammo are you running? try something hot like lake city m193 the OP said "Ammo used: PMC X-Tac, 5.56 NATO 62 gr Green Tip -Lap" which is NATO hot.. he had 0 malfuntions.. just won't hold the BCG back after last round fired.. |
|
Quoted:
Quoted:
sounds like short stroking to me. could be an ammo related issue or gas system issue. what ammo are you running? try something hot like lake city m193 the OP said "Ammo used: PMC X-Tac, 5.56 NATO 62 gr Green Tip -Lap" which is NATO hot.. he had 0 malfuntions.. just won't hold the BCG back after last round fired.. that is short stroking dude... The BCG may have enough momentum to strip off a new round when cycling but not enough to fully lock back the bolt. regardless of the buffer being used a carbine running nato spec ammo should be able to lock the bolt back. the OP has stated that he's tried different mags, that isn't the issue. Troubleshooting from Bravo Company @Pat try the PSA upper with the Bushmaster BCG. Let's see if that changes anything. |
|
Quoted:
that is short stroking dude... The BCG may have enough momentum to strip off a new round when cycling but not enough to fully lock back the bolt. Quoted:
the buffer may be to light/heavy to properly cycle with the new upper.. hence a short stroke or long stroke and the lack of lock-open.. Um.. NoZombies... I was getting at the short stroke issue.. ^^^^^^^^ So yes OP, try swapping the BCG.. |
|
Thanks for the possible solutions to my problem. However, I now have a question relative to short stroking. Is there a reason why my Busmaster A1 Carbine upper doesn't short stroke but the Palmetto does? I even used a 3rd upper that functioned perfectly and didn't short stroke.
Tomorrow I will go back to the range and check to see if the bolt will lock back by pulling charging handle to thr rear following the last shot. I will try some 55 gr FMJ and some other TAP loads to see how the Palmetto upper functions I quess as a last resort I will have to replace the buffer. I sure hope not. PAT. |
|
Quoted:
Thanks for the possible solutions to my problem. However, I now have a question relative to short stroking. Is there a reason why my Busmaster A1 Carbine upper doesn't short stroke but the Palmetto does? I even used a 3rd upper that functioned perfectly and didn't short stroke. Tomorrow I will go back to the range and check to see if the bolt will lock back by pulling charging handle to thr rear following the last shot. I will try some 55 gr FMJ and some other TAP loads to see how the Palmetto upper functions I quess as a last resort I will have to replace the buffer. I sure hope not. PAT. I'm not sure what pulling the charging handle back after firing the last shot will do.... You can just try that with an empty mag at home. There could be a number of reasons, front sight base not lining up with the gas port, incorrect gas port size, damaged gas tube, loose gas key. If you used all of those uppers on the same lower and the PSA is the only one short stroking I would say that you have an issue with the PSA upper. Again, try swapping the bolt carrier group from a different upper and see what happens... |
|
I am presuming your bolt catch works smoothly and freely.
Is the op spring within spec? It seems likely the timing of the Palmetto upper is somewhat different. It could be simple like it is new and tight and needs a lot of lube until it is broken in. Something could be wrong in the gas system. Palmetto could have drilled the gas port a slightly different size. |
|
I had an armorer look at my rifle & Upper yesterday. He said the buffer & spring were OK, the gas key was not loose, and the different magazines used were OK. Without taking the upper apart he said the problem might be the gas tube or the bolt catch.
When I pull the CH back on an empty mag the bolt stays locked back like it should. I was advised by another member to try this operation. Anyway, he advised to fire the upper a few more times to see if the problem might correct itself. If it doesn't then the upper will have to go back. My armorer set my upper to true Mechanical Zero and showed me how to do it. I'm ashamed that my trainers of our AR's have instructed us wrong on how to get to mechanical zero. By the way, it's the same way with a rifle scope. Now it seems so simple. I won't elaborate on how my agency taught us....... PAT. |
|
OK..... I sighted in my PSA upper with MATECH 600 Rear BUIS at 36 yards and the elevation kept on the 300 line like my Armorer suggested after he set the rifle to True Mechanical Zero. My first shot was aprrox. 2 feet low, but dead center. After a few turns up I was dead center. I was still using the 556 Nato PMC X-Tac, 62 Gr. Green Tip-Lap ammo. I also used some Eagle 55 Gr. FMJ and this also shot well...... dead on where I was aiming.
However, the PSA upper still won't lock back on the last shot. I did have it lock back one time........ but that was it. today I was using Adventure line and OK 20 round magazines with the early metal followers. My Armorer wanted me to push up smartly on the bottom of the magazine when I fired to see if this cured the problem. Well, I did...... but no luck. I sent an E-Mail to PSA and am waiting for a response. PAT. |
AR Sponsor