Gunsmithing on-going problem with an Ar-15 upper

[Gunfighter25]

Well, my search-fu sucks but I haven't seen this come up in any thing I've read here.

Problem is my light barrel semi-auto AR-15 will go full auto when I hold the trigger back. At first I thought - bad disconnector. Replaced it. Still had the problem. Okay, check gas rings - replaced them. Still doing it. Okay, maybe gas tube - replaced it. Still more than one shot per trigger squeeze. Replaced the buffer spring with a new one - compared it to the old spring. Longer by a couple of inches - okay worn buffer spring. Nope. Changed out the bolt carrier for a heavier one. Still cranking out more than one shot per trigger pull. Swapped out the lower with a new Rock River lower. no change.

BTW - doesn't matter what kind of load. Everything from M-193s to hand loads that never doubled before.

Ran out of ideas. Would like to keep this upper because it was pretty accurate - sub MOA at 100 yards and light. Any suggestions from the field?

Gunfighter

 

[kz45]

Re: on-going problem with an Ar-15 upper

Are you sure its not slam firing, is it possible you you used Federal primers, dirty bolt firing pin hole, selector switch on full auto?

 

[johncamino]

Re: on-going problem with an Ar-15 upper

Just be careful about posting the fact that you have a full auto (non-class III) AR-15 on the internet. In order for you not to be committing a felony, you need to take active steps to get the problem fixed ASAP (i.e. immediately take to a gunsmith, or send it back to the factory for repair). Even if you isolate it to a type of primers, in the eyes of the BATF you have an illegal full-auto weapon. Take a look at this video:
http://www.cnn.com/video/?/video/bestoftv/2008/03/13/ldt.tucker.govt.guns.cnn

It's pretty scary shit, and now that you've told the world, I would run that to a gunsmith, or send it back ASAP, or you never know.

 

[Kells81]

Re: on-going problem with an Ar-15 upper

What kind of trigger do you have on it and are you sure your using proper technique? My last AR with a JP I would do fine with but other people would have multi's due to the impulse and poor trigger discipline.

 

[biggame10683]

Re: on-going problem with an Ar-15 upper

1. Get it fixed
2. Get out of the AR platform
Problem solved

 

[tomme boy]

Re: on-going problem with an Ar-15 upper

If you swaped out the complete lower with another complete lower, I would say to replace your carrier, bolt, firing pin, and cam pin. I sure sounds like it is slam firing.

 

[FNARSHOOTER]

Re: on-going problem with an Ar-15 upper

Sounds like your bolt has a stuck firing pin. Time for a pro to look at it as it seems your dart throwing aproach is not working.Alot of the things you changed were abit off base for your problem.This is a dangerous problem. Find a smith.
Scot

 

[biner626]

Re: on-going problem with an Ar-15 upper

Gunsmith ASAP! Check the sear spring in the meantime. It may be upside down, broken, etc...

 

[Gunfighter25]

Re: on-going problem with an Ar-15 upper

Thanks all. Yes, the rifle's been looked at by a couple good local gunsmiths. It's now in pieces bound for the scrap pile except for the non-firing systems. No one could figure it out and you guys were the last line of hope for this really good performer.

All of the possibilities you listed were looked at, parts replaced and still...

So like I said, had the upper disassembled and scrapped the bolt, carrier, gas tube and gas block from the upper and fire controls from the original lower. Bagged and tagged for crushing and cutting. Saved all the new parts bought to solve issues like the CS buffer spring, H2 buffer, Speed lock carrier weight kit.

Thanks for the interest and good comments. Got an excuse now for another rifle.

 

[fast freddy]

Re: on-going problem with an Ar-15 upper

ill pay shipping for the parts you dont want. crushing is a bad idea.

Mike

 

[Controlled Chaos Arms]

Re: on-going problem with an Ar-15 upper

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Gunfighter25</div><div class="ubbcode-body">Thanks all. Yes, the rifle's been looked at by a couple good local gunsmiths. It's now in pieces bound for the scrap pile except for the non-firing systems. No one could figure it out and you guys were the last line of hope for this really good performer.

All of the possibilities you listed were looked at, parts replaced and still...

So like I said, had the upper disassembled and scrapped the bolt, carrier, gas tube and gas block from the upper and fire controls from the original lower. Bagged and tagged for crushing and cutting. Saved all the new parts bought to solve issues like the CS buffer spring, H2 buffer, Speed lock carrier weight kit.

Thanks for the interest and good comments. Got an excuse now for another rifle. </div></div>

if you have it handled, fair enough. ...but at the risk of sounding a bit nasty, the smiths you took it too apparently weren't familiar with the AR platform. while they can be hard to diagnose, as is the case with many things over the net, there are only a handful of things that allow this to happen in an AR15... if you haven't given the parts and the rig the shitcan, you're welcome to send it to me. if you've got another plan, then no worries.

...the vast majority of these problems lie in the fire control group - whether it be dirt, galled parts, worn pieces, or some hacker's $25 trigger job, they can usually be fixed pretty quick on the cheap...

and as for announcing you have a full auto weapon that isn't supposed to be, i wouldn't sweat it... if you know it is 'broken' and leave it that way you could get in the stink, but you're actively pursuing a fix, so nobody in their right mind is going to mess with that scenario... however, it doesn't mean it can't happen... lol...