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Posted: 9/29/2012 11:34:47 AM EDT
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I took my Colt LE6920-MP to the range for the first time this morning, shooting a total of 100 rounds.
Although I didn't use the crazy advice from my LEO friend (to pour motor oil down the barrel after the first mag) I DID clean the barrel after the each 20 round mag with Breakfree CLP. Here is my question: I loaded each mag with 20 rounds and out of 5 magazines, the bolt didn't lock open after the last round 2 out of 5 times. I know a gun may need to "break in" but wanted to see if this is anything I should be concerned about. Other than that, there were no other issues whatsoever. No jams or anything. I used PMC bronze 55 grain primarily but did shoot one 20-round box of MFS 62 grain ballistic tipped zinc plated steel cased ammo. TIA for your responses!! |
I had a similar issue with my LE6920, but I can't confirm whether or not mine was from being new, or because I changed some important parts before I ever fired it. I swapped the standard FSP and handguards for a low profile gas block and free-floating rail, and then shot it for the first time. It did the same thing as yours, so I started loading 2 shots per mag to try and see what was going on. It continued for the day, and I was pretty frustrated, but then then next time I shot it, it worked perfectly, and has worked perfectly ever since. And I do mean perfect
Hopefully if you keep up the shooting it will resolve itself. Your likely ammo is fine. For what it's worth, I have 2 other Colts, a 1991 era Sporter HBAR and an unfired SP6920. The Sporter is a champ, I have never known it to ever suffer a problem of any kind, and obviously the SP6920 has yet to prove itself. |
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Did you clean it before you took it out to the range for the first time?
Also, cleaning the barrel after each whatever amount to "break in" is not needed on chrome lined barrels. Give the whole gun a really good cleaning and see what happens next time you go out. Only load 1 round per mag, that way it should lock back after every shot. Also, what mags were you using? |
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Try splurging on some quality 5.56. Not saying pmc or the mfs is crap, it's just doesn't have the extra kick in the pants some 5.56 brings to the table. I'd get 200 rounds or so of good 5.56, and shoot it like you normally would. If you continue to have problems, we can at least rule out needing brake in.
You also need more then two magazines, a good rule of thumb is "too many to be logical." welcome to the party. |
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Try splurging on some quality 5.56. Not saying pmc or the mfs is crap, it's just doesn't have the extra kick in the pants some 5.56 brings to the table. I'd get 200 rounds or so of good 5.56, and shoot it like you normally would. If you continue to have problems, we can at least rule out needing brake in. You also need more then two magazines, a good rule of thumb is "too many to be logical." welcome to the party. It should run fine with PMC. This shouldn't happen, but maybe it's a problem with your mags. Do you have other mags you can try? I would take it to the range again, and if it happens again I would call Colt about it. |
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Sounds like a magazine issue.
Mark or number your magazines, and keep note of which ones are failing. If one fails consistently, replace it with a new one and keep the defective ones for parts or training. If all of your magazines fail frequently, then I would start by replacing the bolt catch or maybe trying a different weight buffer? I'm not sure which buffer would help, I've never had a desire to change any of my buffers, so I haven't looked into it much. Others here could probably help you out in that regard. |
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Did you change the Buffer weight or action spring?
It shouldn't be short stroking, even if its new. I would blame the mags if you haven't changed anything else on the rifle. But those are quality mags, so for both of them to have the same issue is strange. Maybe there is an issue with the bolt catch being stiff, or sticking, or something like that now that i think about it. |
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Yes I cleaned it before taking it out. Lubed it real well also. I was using the two Magpul mags that came with the Colt. The 20rd PMAGs are known to be problematic. Try some 30rd PMAGs or some USGI aluminum mags or some Lancer AWMs. I'm pretty sure the 6920MP comes with 30 round magazines... I'd shoot a couple hundred rounds with full power 5.56 and I'd bet you wont have another issue. |
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Yes I cleaned it before taking it out. Lubed it real well also. I was using the two Magpul mags that came with the Colt. The 20rd PMAGs are known to be problematic. Try some 30rd PMAGs or some USGI aluminum mags or some Lancer AWMs. I'm pretty sure the 6920MP comes with 30 round magazines... I'd shoot a couple hundred rounds with full power 5.56 and I'd bet you wont have another issue. Sorry, he said in the OP that he was shooting 20 shots per mag so I automatically assumed they were 20rd mags. I agree with tstanfield12's suggestion to shoot full-power ammo such as XM193, XM855, PMC X-Tac, Q3131, etc. |
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Yes I cleaned it before taking it out. Lubed it real well also. I was using the two Magpul mags that came with the Colt. The 20rd PMAGs are known to be problematic. Try some 30rd PMAGs or some USGI aluminum mags or some Lancer AWMs. I'm pretty sure the 6920MP comes with 30 round magazines... I'd shoot a couple hundred rounds with full power 5.56 and I'd bet you wont have another issue. Sorry, he said in the OP that he was shooting 20 shots per mag so I automatically assumed they were 20rd mags. I agree with tstanfield12's suggestion to shoot full-power ammo such as XM193, XM855, PMC X-Tac, Q3131, etc. I've shot about 500 rounds of PMC Bronze 55gr through a couple rifles and I haven't had any issues with the ammo. I would guess it's a magazine issue, though trying different types of ammo wouldn't hurt. I would want to know my gun could handle any type of ammo, and I would think it should definitely run fine on any brass cased ammo. |
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Try splurging on some quality 5.56. Not saying pmc or the mfs is crap, it's just doesn't have the extra kick in the pants some 5.56 brings to the table. I'd get 200 rounds or so of good 5.56, and shoot it like you normally would. If you continue to have problems, we can at least rule out needing brake in. You also need more then two magazines, a good rule of thumb is "too many to be logical." welcome to the party. THIS, get some (NATO: SS109; U.S.: M855) and let it rip. |
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Yes I cleaned it before taking it out. Lubed it real well also. I was using the two Magpul mags that came with the Colt. The 20rd PMAGs are known to be problematic. Try some 30rd PMAGs or some USGI aluminum mags or some Lancer AWMs. I'm pretty sure the 6920MP comes with 30 round magazines... I'd shoot a couple hundred rounds with full power 5.56 and I'd bet you wont have another issue. Sorry, he said in the OP that he was shooting 20 shots per mag so I automatically assumed they were 20rd mags. I agree with tstanfield12's suggestion to shoot full-power ammo such as XM193, XM855, PMC X-Tac, Q3131, etc. I've shot about 500 rounds of PMC Bronze 55gr through a couple rifles and I haven't had any issues with the ammo. I would guess it's a magazine issue, though trying different types of ammo wouldn't hurt. I would want to know my gun could handle any type of ammo, and I would think it should definitely run fine on any brass cased ammo. I think the points suggested above to use "full-power ammo" is to work out the "stiff", i.e. -needed some "full-power ammo” to break-in and help smooth out the action. |
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I'll definitely try some more quality ammo, although I've always heard that he PMC is pretty decent. It was also a good suggestion to pay attention to which mag is doing it because it could have been the same one both times.
I noticed the 2 times I cleaned it that the bolt fits very tightly in the bolt assembly. It doesn't just slide in but needs a little push to get it in. I assumed this is normal but just wanted to mention it in case that's not the case. (Remember, I am a newbie on AR's.) Thanks for all the help!!! |
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IT'S NOT AMMO -
PMC is within m193 ammo loads, if anything it is hotter: PMC 3200fps at the muzzle Federal 1165fps OP, shoot another 100rds, then get a few more mags, number them, and then load 1rd in each - do it say 20 times evenly between mags. Report back what happens. |
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IT'S NOT AMMO - PMC is within m193 ammo loads, if anything it is hotter: PMC 3200fps at the muzzle Federal 1165fps OP, shoot another 100rds, then get a few more mags, number them, and then load 1rd in each - do it say 20 times evenly between mags. Report back what happens. What barrel length was used for that PMC test? Based on my own personal experiences with it, I don't believe your claim that it is just as powerful as XM193. |
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IT'S NOT AMMO - PMC is within m193 ammo loads, if anything it is hotter: PMC 3200fps at the muzzle Federal 1165fps OP, shoot another 100rds, then get a few more mags, number them, and then load 1rd in each - do it say 20 times evenly between mags. Report back what happens. What barrel length was used for that PMC test? Based on my own personal experiences with it, I don't believe your claim that it is just as powerful as XM193. That isn't my claim - the links go to each respective manufacture's website. PMC is tested to be hotter. As far as my experience - It appears to be very close. I don't see any measurable difference in POI with any sighting system on my ARs - ACOG, scope, irons, RDS. Never have cycling issues with it running it through my adjustable gas system for 3gun which was set with m193 ammo. Ballistic calculations are close as well with input of the respective data. I just sent an email to PMC asking what barrel length just to be clear but even then you're talking less than a 100fps difference. They test their xm193 from a 20". Federal listing of American Eagle 62g/m855 ammo for LE appears to be slower (3020fps) and from a longer test barrel (24"). Their American Eagle 55/m193 is 3240 from a 24". |
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Quoted: IT'S NOT AMMO - PMC is within m193 ammo loads, if anything it is hotter: PMC 3200fps at the muzzle Federal 1165fps OP, shoot another 100rds, then get a few more mags, number them, and then load 1rd in each - do it say 20 times evenly between mags. Report back what happens. FPS at the muzzle does not necessarily equate to pressure. Generally the higher FPS would be a higher pressure but its not a rule. There are .223 saami loads that are faster then 5.56 nato rounds. |
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PMC Bronze is indeed one of the slower .223 loads available.
The manufacturer info is from a 26" barrel or something. There is chrony data available via google or site search. PMC Bronze is SLOW O.P., the bolt being snuf in the carrier is no problem. Mark your mags with a marker or tape so you can identify ones that have issues. Try different mags first. Take the upper off and manually push and pull the bolt catch to see if its sticking. And again, you didnt add a heavier buffer or buffer spring did you? |
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PMC Bronze is indeed one of the slower .223 loads available. The manufacturer info is from a 26" barrel or something. There is chrony data available via google or site search. PMC Bronze is SLOW O.P., the bolt being snuf in the carrier is no problem. Mark your mags with a marker or tape so you can identify ones that have issues. Try different mags first. Take the upper off and manually push and pull the bolt catch to see if its sticking. And again, you didnt add a heavier buffer or buffer spring did you? No, I haven't changed anything on it at all. It is stock from front to back. |
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I can always count on some sort of goofyness from the 20 round magpuls that I have. Try some other types of mags as has been suggested. at least try this first . Since it's the easiest first step. GD I was using 30 round mags, just loading 20 rounds at a time. I will try marking the mags like others have suggested. |
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I dont care what velocity bronze is advertised as. Its a lighter load than federal 223 and m193 and m855. Anyone can tell if you just shoot them back to back.
That said, its not the ammo, its still good stuff. My first guess is the mag, 2nd would be a gas leak causing a slight short stroke.... |
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IT'S NOT AMMO - PMC is within m193 ammo loads, if anything it is hotter: PMC 3200fps at the muzzle Federal 1165fps OP, shoot another 100rds, then get a few more mags, number them, and then load 1rd in each - do it say 20 times evenly between mags. Report back what happens. Your wrong, pmc bronze is know as weak for a reason Click and learn |
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So it didn't lock back some of the time? But not always? Sounds like short stroking. magazine engagement of the bolt catch even if all the worst tolerance stacking in the world happens, is pretty good. That's barring something being truly wrong. The locking back near half the time would show it at least can work.
It may not be ammo, the gas port could be undersized, a leaky gas tube, or a burr in the carrier bore, bla bla, or everything is still rough as its still new. With good magazines I don't know why some of you are so eager to jump on magazines. Two mags failing in a similar fashion? Not likely, two pmags? Even less likely. |
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So it didn't lock back some of the time? But not always? Sounds like short stroking. magazine engagement of the bolt catch even if all the worst tolerance stacking in the world happens, is pretty good. That's barring something being truly wrong. The locking back near half the time would show it at least can work. It may not be ammo, the gas port could be undersized, a leaky gas tube, or a burr in the carrier bore, bla bla, or everything is still rough as its still new. With good magazines I don't know why some of you are so eager to jump on magazines. Two mags failing in a similar fashion? Not likely, two pmags? Even less likely. It wasnt said that it was both. OP said it could easily have been just one... Read the thread..... And FWIW that is the very first place to start troubleshooting.... |
| All my AR's run fine on PMC Bronze .223. The PMC 5.56 is hotter but not required. PMC is great stuff now, years ago it was lower powered than now and those old stories keep surfacing and seem to have a life of thier own. Both the PMC .223 and 5.56 is great stuff, reliable, accurate, and clean. And the brass is great for reloading as well. I agree, shoot it a couple of hundred more rounds and then if you still have problems look at the mags. I have read but cannot confirm that 20 round P-Mags have been reported to be problematic....good luck and enjoy shooting it....<><....:) |
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Yeah, it could have very well been the same mag failing. I really can't say for sure. Thats the first thing I will check and then I will report back to see what I found.
I will be really relieved if thats all it is. I was hoping it was just a part of being new and just not "broken in". Based on the feedback, I am a bit more worried now.... |
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IT'S NOT AMMO - PMC is within m193 ammo loads, if anything it is hotter: PMC 3200fps at the muzzle Federal 1165fps OP, shoot another 100rds, then get a few more mags, number them, and then load 1rd in each - do it say 20 times evenly between mags. Report back what happens. Your wrong, pmc bronze is know as weak for a reason Click and learn Alright then from that it would be slow. That thread is 2 years old though. Who has a chrono to do a recent test? Still doesn't change that I haven't seen any reliability issues with cycling with my adjusted gas system that was adjusted with Federal xm193. ETA - Just checked my ballistics calculator and I have in 3200fps for load data, now compared to the say 2825fps from the privately tested chrono info. I do not see the 3" difference at 300yd nor the 4" difference at 350yd. |
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