AR Trouble..help please?

[LPPOsecurity]

So the last time I took my AR out my friend was shooting and said it was firing two shots at once a couple times but I couldn't get it to do it, but while out today it was occurring like every mag, could this just be a dirty gun or do I have another issue possibly, this is a fairly new, unaltered LE 6920, could somebody offer some light on this situation?

 

[Ljungman]

this may be a sear issue and may get you into trouble very quickly if not corrected ASAP. It may be that in your lower something is interfering with the "hook" on your sear from catching your hammer and causing the multiple shots. this can run you afoul of local Law enforcement. Personally i would clean thoroughly and begin investigating the workings of the lower. take off the upper and play with the hammer/trigger in your lower. Watch as you pull the trigger and the hammer falls. If all is with in norm..ok. While holding the trigger back push the hammer back. Watch as the hammer catches the sear the first time, then let go of the trigger and see if the 2nd hook catches the hammer on reset. if this at all fails- immediately stop shooting rifle and replace your sear/hammer pack. easy fix (well kinda frustrating) but not complex. Even better have a local armorer look into it. better to spend some cash to get it right than have a nice vacation courtesy of uncle Sam. If your rifle is firing more than once per trigger pull it qualifies as a "machine gun" and is in violation of the NFA. Good luck on your journey. If you are nearby Camby, Indiana..i recommend you take it to Bradis. Those guys have been nothing but good to me and my brother/friends.

 

[sloughfoot]

The previous is good advice.

I will add that maybe you are "floating" the trigger. In other words, you need to press the trigger all the way to the rear in recoil. If you are letting the trigger "float", recoil can allow the rifle to fire a second time. It is a common occurance with otherwise legal two stage military triggers in the M1 and M1-A and AR-15

If that is not what is going on, this highly illegal condition needs to be repaired by a pro.

 

[Gabriel]

take off the upper and play with the hammer/trigger in your lower. Watch as you pull the trigger and the hammer falls. If all is with in norm..ok. While holding the trigger back push the hammer back. Watch as the hammer catches the sear the first time, then let go of the trigger and see if the 2nd hook catches the hammer on reset. if this at all fails- immediately stop shooting rifle and replace your sear/hammer pack.

This. When checking the sear engagement when letting go of the trigger, do it slowly. It's possible the second round being fired is actually being fired as you begin letting off the trigger.

Depending on how you are shooting/holding the rifle, you also may be inadvertently bump firing it and not realizing it. However I take it that the problem seems to be becoming more frequent, so I'd look at the disconnector/hammer engagement and the disconnector spring itself.

 

[praff]

I had the exact same issue on a spikes lower that I built for an sbr. I was getting doubles occassionally right after I built it. Didn't seem to do it all the time and was worse on some uppers vs others. I chased my tail for a week or so thinking it was timing on the upper, wrong buffer, too fast of action, etc. However, the problem actually turned out to be the disconnector/hammer interface. I went to a local store, paid for a set, and they gave me a handfull of hammers/disconnectors until i found a combination that worked. I returned the others to them. My issue was with a daniel defense lower parts kit going into a spikes lower. My understanding is that the geometry between diferent lowers and diferent trigger groups can be off by mere thousanths and cause this issue. Additionally, my trigger group would function check perfectly until it came to "live" fire. My suggestion would be to swap out the disconnector/hammer with a known good combination from another lower or see if someone can loan you a couple till you find one that works. The other alternative is to go to a high dollar trigger like a mccormick or jewel. Eventually, I did this anyway and was very happy with the results. I probably still have a handfull of disconnectors and hammers that I would be more than willing to loan you until you found a combo that worked. Lemme know.

Even tho this is a factory built lower, I wonder if this issue couldn't have reared its ugly head after a little wear or if the trigger group holes are out of spec? Just my 2 cents.

 

[Hop]

And this is a Colt LE 6920??? That's pretty unusual. Does the disconnector spring back normally when you push it or does it stick?

 

[Hazwhopper]

Do you reload? If so, you could be pushing the primer in, but not all the way.
When I was putting mine into battery, the weapon went off and chambered another round. The second round had a very slight dimple on primer, very slight. But was there. I checked the rest of mag by pulling the charging handle and unloading the magazine, and everyone of the brass had a very slight dimple on primer. Mine might be a different problem but just a thought.

 

[Classic]

The previous is good advice.

I will add that maybe you are "floating" the trigger. In other words, you need to press the trigger all the way to the rear in recoil. If you are letting the trigger "float", recoil can allow the rifle to fire a second time. It is a common occurance with otherwise legal two stage military triggers in the M1 and M1-A and AR-15

If that is not what is going on, this highly illegal condition needs to be repaired by a pro.

Had this happen with a brand new M1A. Thought for sure there was something wrong with the weapon. Nothing wrong with the M1A, just wasn't pulling the trigger all the way thru.

 

[Litlratt]

Do you reload? If so, you could be pushing the primer in, but not all the way.
When I was putting mine into battery, the weapon went off and chambered another round. The second round had a very slight dimple on primer, very slight. But was there. I checked the rest of mag by pulling the charging handle and unloading the magazine, and everyone of the brass had a very slight dimple on primer. Mine might be a different problem but just a thought.

It's easy to tell the difference between hammer follow and a high primer in an AR.
The primer will appear normal in a case where you experienced hammer follow. In a case that had a high primer, the primer will have a nipple instead. As there is no hammer pressure against the firing pin, the pressure from the fired cartridge will push the primer cup material back into the firing pin hole.

 

[ryknoll3]

A slight dimple in the primer is perfectly normal on round that is chambered but not fired. The AR has a floating firing pin which will tap the primer during chambering due to the inertia of the pin. This is normal and doesn't hurt anything.

To clarify a couple of things. The AR doesn't have a two-stage trigger out of the box, so similarities between that and the older guns (M1 Garand and M14/M1A) are out.

As others have said, it is most likely a problem with the hammer or disconnector. The disconnector is that little hooked piece that sits on top of the trigger. When you fire the gun, the retracting bolt cocks the hammer and a notch on the back of the hammer engages the disconnector, holding the hammer back. When you let off on the trigger, the disconnector rocks back and releases the hammer, which falls ever so slightly forward and reengages with the triggers sear surface.

To test for proper function, take the upper off. Make sure the hammer is cocked and while holding the hammer with your thumb, pull the trigger and let the hammer ride forward. Now, while STILL holding the trigger back, recock the hammer. It should hook on to the disconnector. SLOWLY release the trigger to its forward position. In a proper functioning gun, the hammer should release from the disconnector and move very slightly forward and stop when it reengages the trigger. If the hammer wants to fall completely forward instead of stopping on the trigger (never let the hammer strike the rear of the mag well, it can crack something) either your disconnector hook is too short, or the notch on the hammer is too short. A swap of hammer and disconnector should fix your problem.