So today I went to an indoor range to test fire and and try different ammo types with my newly built AR-15. I first fired XM193, PMC, Wolf (to test steel case), then Prvi Partisan. My last trigger pull on the magazine loaded with Prvi Partisan 69gr appeared to have fired 2-3 rounds. These were the last rounds in the 20rd PMag I was using.
This is on semi-auto using a LMT full-auto bolt carrier group with a USGI trigger from G&R Tactical’s LPK. (I think it is also LMT.)
Now, I’m not 100% sure what happened. I had been making slow and smooth trigger pulls. I don’t remember double tapping the trigger. I do remember hearing 2-3 shots very quickly and the gun jerked a lot further to the left than it had previously (I was firing left handed). I’m not sure if more than one round even came out. I wasn’t counting up to that point. Maybe the extra shots I heard were just other pistols on the range.
What I want to know is - Is it possible for some malfunction somewhere in the gun to cause 2-3 rounds to fire on a single trigger pull on a semi-auto trigger?
Yes and it is an issue that needs to be fixed. The lpk install is the first place to look.
Do a search on doubles and you will get a ton of possible causes and fixes. With the setup you have I would be inclined to believe it is in the install and not bad parts.
Someone more in the know than myself will be along but I wonder if being new could be a cause. A little burr or something.
As for the disconnector spring, I believe it is sitting in there with the wider end on the bottom. I’ll have to check it when I get back from vacation.
That’s interesting you say that, he states that he has a G&R lpk. Is something possibly starting to come out here? Uh no,no,no I uh definitely didn’t mean to refer to them as “dog shit” parts hahahahaha
Pull the trigger and ride the hammer forward so it doesn’t slam against the lower.
-Keep holding the trigger to the rear and push down on the hammer. The hammer should stay down.
-Let the trigger forward. The hammer still should not release.
Do this a bunch of times.
If the gun fails this test and the LPK is verified to be installed correctly, there is something faulty with either the LPK (probably the disconnector) or with the lower…more likely the problem is with the LPK.
Start by replacing the LPK (really just the fire control group, or FCG).
I’m honestly not sure how it’s possible to not know if the gun doubled or tripled. Seems like something you would be sure of if it happened.
If it fails the above test you’ll know for sure. But it could pass 99 times and fail once. So for your own peace of mind you should replace the FCG anyway. That’s what I would do at least.
I experienced a couple double-fires at the range recently, and when I was cleaning the AR afterwards, there was a drag on the firing pin when disassembling and re-assembling it. I pushed a pipecleaner thru the firing pin hole in the bolt carrier and out popped a piece of cleaning cloth… No more double-fires now.
I’ve had two different Stag/CMT made FCG that did this
I had posted about it a while ago
I found that the hammer would fall on release of the trigger
Stag was always good about replacing for free but gave no idea of why it was happening…I did find some differences in dimensions between the disconnectors but like i said it’s happened to me twice
http://youtu.be/h4F7hi3-i7c this video was from my first problem I had since replaced the trigger with a new one but had the same issue last year during a class with Mike Pannone once again replaced
I have had a couple of 2 fers with my Timney Trigger but it is just a bump fire because of the light trigger pull. Wish I could do it on demand, super fast double taps would be great
No more double-fires now.