Bushytale, while you are correct about how to check the disco, it seems this is not going to be the prob, as in this case, the gun would fire full auto. Instead, its only firing a second shot upon release of the trigger. So, as T-Bob above has explained, I’m thinking its the trigger or hammer sear surfaces. Could also be stuck primer etc I suppose. I know I’ve also heard of backward disco springs in other weapons as being the cause for this same malf, but not sure if this is possible with the AR. It’s been awhile since I’ve done any fcg work, or any armorer work for that matter.
The one time I accidentally put a disconnector spring in upside down the ar went full auto, didn’t just double.
Doesn’t Colt have a lifetime warranty on parts?
I prefer to call it uncontrolled slamfires.
If you are not sure what you are doing, you may not be able to recognize a problem even after all of the pointers we give you. If you can find an AR armorer who won’t charge an arm and a leg, take it to him and let him check the rifle.
Quite sure I can diagnose and handle it. Never met a local armorer or gunsmith I trust. Besides, these are simple little guns, and fun to work on. Just like to come here to discuss first, beforehand sometimes.
Someone asked earlier, “why doesn’t my brother contact Colt?”. He did. They said he must overnight it to them which cost around $100. I do not know if colt had offered to pay return shipping or not. I’d much rather fix myself for him. Anyone can do armorer work. Ok, maybe not anyone, but anyone even slightly mechanically inclined can. Thx for all the replies thus far.
I can understand your brother not wanting to send the rifle back to Colt due to the cost of repair compared to the value of the rifle. As long as it is not a duty rifle, making your own repairs is not that big of an issue. You could buy a whole new FCG for less than the cost of shipping and repair.
If you want to do your own work I suggest you buy a good book on AR rifles with a troubleshooting guide and plenty of illustrations. If you start doing more extensive repairs, I recommend investing in a set of roll pin punches.
Razorhunter, if the disconnector is only very slightly out of spec it may not cause it to go full auto. If you inspect the disconnector and the sear surfaces of the hammer and trigger and all appear normal, do the check that I recommended. You may have to repeat the test a few times, releasing the trigger ever so slowly, to make it happen. If it fails to hold the hammer back when the hammer transitions from the disconnector to the sear, it may only need a slight adjustment or a new disconnector. I have fixed this problem on a few parts builds, as this comes up occasionally when you get tolerance stacking.
If you don’t understand how these parts function together take it to someone who does.
Thx Bill, I don’t often boast, nor do Ipost in any manner that would aindirectly dvertise or show off my armorer skills as some members do, but I am very familiar with the AR and AK platforms, and I have most of the armorers tools necessary. When it comes to issues like this however, I still like to come here to discuss said issue, before I break out the armorers tools etc. I don’t claim to be an expert, but I can hold my own. I’ve built an AR or two. That said, it never hurts to ask and get opinions/experiences etc, as there is always something new to be learned, especially on this forum with all of its great members and vast wealth of knowledge. Thx so much guys. I will keep you guys updated as to what I find.
Please let us know what you find out and which parts you have to replace. Pictures would be good if you can manage it.
7Ring, most definitely brother.
+1. If someone did their own trigger job and tried to polish the trigger/ hammer sear surfaces, the could have gone too far with it.
Rootbrain
stop spreading FUD. no agency is going to arrest you for a genuine parts failure.
If you leave the rifle as is and “enjoy” the new found non semi auto functioning that is a different story.
BUT if you have a genuine parts wear out, failure or mistake in gunsmithing there is NOTHING to worry about IF you take the gun out of action and take reasonable steps to fix the malfunction in a timely fashion.
Sounds to me like the disconector is not properly timed. Perform the above test and of the hammer falls during the trigger reset, you need to modify the disconnector. The part on the disconnector that rests on the trigger, and limits its forward travel, will need to be filed on the bottem to allow the disconnector to travel forward more and disengage the trigger latter in the reset. Just go slow annd check often. If you take too much off, the disconnector will not disengage the trigger at reset. I have had to do this on a few rifles that were built with CMT LPK’s. I was also a frequent problem back in the 80’s and 90’s when parts were not made to a higher quality. Or you can go the easier route and just by a few disconnectors and swap them out until the issue is fixed.
Now would be an excellent time to install a Gieselle ssa trigger set!!! Never let a crisis go to waste!!
Is your brother bench shooting? I’ve seen people shooting from a supported position not pull the rifle in tight enough to their shoulder and it would cause the rifle to bump fire. FCG inspection revealed everything was ok internally.
I had the same issue.
Found out debris (blown primer cup) was resting in the sear notch/hammer interface.
When trigger was released the disconnector let go of the hammer. The sear failed to trap the hammer due to the debris and it continued forward lighting off the next round.
Occurred in an LMT lower with OEM FCG.
Razorhunter,
Any update? I’m curious to find the cause.
Devilneck
Sorry, not yet guys. Promise to have one soon tho. That’s because the update I do have is that my son Jax was just born and my brother’s Colt had to take a backseat! 9lbs 4oz! He’s a linker! The irony is that we’re both very slim/fit individuals lol. Will give Colt update soon.
Congratulations on your new son.
I bet the problem is caused by the disconnector releasing the hammer too early. This causes the hook on the hammer to miss the sear and the hammer falls.
This condition will not necessarily cause the rifle to go full auto because after it fires on release the trigger is forward and the sear catches the hammer stopping it from falling again.
The fact that the rifle only fires on release and not continuously suggests the hammer/sear are working correctly.