Colt AR Bolt Cycling Issue

[Buzz70]

I purchased a a brand new Colt AR Carbine like a year or so ago. When I purchased it I put approximately 60 rounds through it with no problems. I cleaned it and in the safe it went. Next time I took it out I had failure to feed issues with almost every round. The rounds seem to eject fine; however the next round gets wedged between the bolt and the barrel (*Note rifle has M4 feed ramps). When I hand cycle a round it feeds just fine. Only has a failure when cycling automatically. Took it home cleaned it and discovered the gaps on the gas rings on the bolt were all lined up perfectly. Figured that may have been the issue so I alternated the gaps in the rings and put it back in the safe. Took it out for the third time yesterday and again was having FTF issues. I switched magazines and had the same issue. I ran the ammo and same magazines with my Smith/Wesson AR and it ran flawlessly through a couple hundred rounds. The Colt wouldn't make it through 1 or 2 rounds without failing to feed, either the round didn't load at all or it wedged between the bolt and barrel. When I got home and cleaned the guns I was comparing the bolt carrier groups. I checked my Colt against two other AR BCGs. The only thing I notice is the Colt bolt is extremely difficult to move back and forth in the bolt carrier. In the other two ARs the bolts move with ease in the bolt carrier. I tried this little test with the bolts dry and lubed with same results. I don't know if Colts simply have a tighter tolerance or if this could be the issue. So I'm looking for advise here. I'm getting frustrated. My other ARs run fine; however the more costly Colt is having issues.

I suppose it could be the ammo I'm using, but again I don't know why it would work flawlessly in two Smith & Wesson ARs with the same magazines and not the Colt. For the range I'm using Tula 55gr FMJ in .223. I didn't have any other ammo with me, so couldn't test that theory. But again I'd be disappointed if two of my ARs eat/shoot any ammo and my Colt has problems.

So could it be under powered ammo causing the bolt to short cycle?
Is there something wrong with the bolt/carrier tolerances?
Steel cased ammo?
Need a lighter buffer?

Please help and thanks.

 

[uncle money bags]

First, lets get the gaps in the gas rings myth out of the way. It doesnt matter where they are lined up.
The tightness between the bolt and BCG is normal and will wear itself in and become looser as time goes by.

Tula .223 ammo is weak, but it should still cycle. however, the Colt is designed around the 5.56 round which is a higher pressure and it is not uncommon for it to choke on lower pressure rounds until it has loosened up. Combined with using steel case ammo, which does not obturate like brass cased ammo allowing blow by which fouls the chamber and provides less gas to the system can cause this problem initially. To test this, take one of the BCG's from one of the other known good rifles and install it in the Colt and check function with live fire. If it works fine then it is just a matter of breaking in the Colt until it will work with lower pressure rounds consistently. In the mean time, pay particular attention to making sure the chamber is cleaned. The blow by from steel cased ammo leaves more residue in the chamber than brass cased and can cause malfunctions by retarding the extraction sequence. this is a particular problem if you switch to brass cased after shooting steel cased without cleaning the chamber.
Using cheap ammo has its positives and negatives, and attention to a cleaning regimen focused on keeping the chamber cleaned is one of the trade offs.
My recommendation is to shoot a couple hundred full power 5.56 rounds (M193 or M855) through a well lubed, spec AR before trying to shoot steel cased ammo.
To reiterate, more than likely this is not an issue with the rifle, and you have already tried separate magazines, so the issue is probably tighter tolerances which will work themselves out with use.

 

[Buzz70]

First, lets get the gaps in the gas rings myth out of the way. It doesnt matter where they are lined up.
The tightness between the bolt and BCG is normal and will wear itself in and become looser as time goes by.

Tula .223 ammo is weak, but it should still cycle. however, the Colt is designed around the 5.56 round which is a higher pressure and it is not uncommon for it to choke on lower pressure rounds until it has loosened up. Combined with using steel case ammo, which does not obturate like brass cased ammo allowing blow by which fouls the chamber and provides less gas to the system can cause this problem initially. To test this, take one of the BCG's from one of the other known good rifles and install it in the Colt and check function with live fire. If it works fine then it is just a matter of breaking in the Colt until it will work with lower pressure rounds consistently. In the mean time, pay particular attention to making sure the chamber is cleaned. The blow by from steel cased ammo leaves more residue in the chamber than brass cased and can cause malfunctions by retarding the extraction sequence. this is a particular problem if you switch to brass cased after shooting steel cased without cleaning the chamber.
Using cheap ammo has its positives and negatives, and attention to a cleaning regimen focused on keeping the chamber cleaned is one of the trade offs.
My recommendation is to shoot a couple hundred full power 5.56 rounds (M193 or M855) through a well lubed, spec AR before trying to shoot steel cased ammo.
To reiterate, more than likely this is not an issue with the rifle, and you have already tried separate magazines, so the issue is probably tighter tolerances which will work themselves out with use.

Thanks UMB,

Next time I go to the range I plan to take multiple brands of brass cased ammo and have some CLP on hand. I'm hoping this is the case. Oh and thanks for the info about the gas rings, I was always told it did matter.

 

[Shootin 4 Fun]

I'm with UMB, try better ammo and a few different magazines. The issue is probably not with the rifle itself.

 

[Buzz70]

Picked me up some Winchester 5.56 M855 62gr ammo this evening. Hope to get out soon to test fire. Thanks for the advice. I'll post back results.

 

[Fyrtwuck]

If you still have the same problems, try switching the BCG, buffer and spring from one of your other rifles. Also check your bolt carrier key and make sure it is tight and the bolts holding it to the carrier are staked to hold them in place.

Compare the weights of the buffer with the buffers of your other rifles. Try to find a way to compare the spring tension of the buffer springs.

Make sure you have enough lube in the rifle.

 

[Fyrtwuck]

First, lets get the gaps in the gas rings myth out of the way. It doesnt matter where they are lined up.

Tell me more. This is the first time I've read this. I had it pounded into me in basic and ever since that they had to be staggered.

 

[uncle money bags]

Yeah, I had the same experience and I do not know the origin of the bad info. What I do know is that it is false, proven through actual use over multiples of rifles and shooters. In fact, I have seen ARs run just fine with one gas ring. I wouldnt recommend it, and if there was an alternative like replacement rings available, it wouldnt have been done in those cases. I have heard about one particularly over gassed ar run without rings altogether, but I doubt it would have if the gas port had not been way too large.

So, whats the latest OP? Your feedback may help others who have the same issue.

 

[SMS]

Tell me more. This is the first time I've read this. I had it pounded into me in basic and ever since that they had to be staggered.

Basic training instructors who think they are firearms experts by virtue of their duty position...they tend to be the worst purveyors of gun myths.

 

[Buzz70]

Thanks for the additional information. I purchased the ammo mentioned above; however haven't got back out just yet. I will double check the key, but I think it's fine. If I continue to have a problem I am going to switch out the BCG from one of my other rifles for a test. I will bring back results here, but it may be a couple more weeks. I wish I lived in the country so I could just go out on my own property to test fire....but sadly I don't.