AR doubled?

[ny32182]

So I was out shooting with a friend on Wednesday afternoon. I was dumping a mag as fast as I could pull from my Bushy Superlight. I can pull pretty fast, but both me and my friend who was standing there feel that the gun doubled once in the middle of the mag dump.

The gun has a little under 2K rounds through it and has never malfunctioned in any way, except for one last round fail to feed from a bad magazine. It has no rifle-at-fault malfunctions ever, except for possibly now this.

What could cause this? I know the usual suspect is the disconnector. But 2K rounds? Thats not a lot. FWIW, I think it is a possibility that I MAY have somehow bump-fired the second round of the 2 round burst. At least, I feel it is a distinct possibility.

I dumped another mag, and also did a mag of slower fire specifically holding the trigger down after each shot to ensure correct function. When I got home I function checked the lower every which way possible, but there was no further indication of any possible malfunction.

Thoughts? I hope I just bump fired the second round by accident.

 

[ARperson]

hmmmm....

possible it just bump fired. Was the rifle shouldered?

possible slam fire. (though not likely) What kind of ammo were you using?

possible cook off (though not likely since there was very little time in the chamber) But if you had done plenty of mag dumps from a light weight barrel, they can get pretty hot. The barrel wasn't glowing was it?

 

[ny32182]

The rifle was shouldered. I was lighting up a propane tank from a gas grill, from about 30-40 yards away. (yes, it was empty).

Slam fire is possible I suppose. Ammo was Georgia Arms canned heat 55gr FMJ; my usual plinking ammo. Maybe there was just a super-soft primer on one of the rounds.

I doubt it was a cook off. No way that second round was in the chamber anywhere near long enough to cook off. The barrel was smoking but not glowing.

I hope I just somehow bump fired it.

 

[Bartholomew Roberts]

Have you run a function check on the rifle per the manual? This will indicate whether you have a problem in your fire control group or whether it was just an inadvertent bump fire.

 

[ny32182]

To function check a lower, I start with the hammer and trigger both released, and cock the hammer. Pull and release trigger, hammer falls. Cock hammer. Pull and hold the trigger. Hammer falls. Cock hammer with trigger still held. Release trigger. Hammer "clicks" forward just a little bit but doesn't fall. Pull trigger; hammer falls. Check to make sure the safety is working... if it passes these tests, I consider the lower to be working fine. Am I missing something?

The only other thing I can think of is that some surface on the disconnector or hammer has been worn slick and somehow released when it wasn't supposed to. Though the hammer doesn't appear to be "on the edge" of releasing when cocked, as I pulled on the hammer while it was cocked, both with the trigger held and not held, and it wouldn't come forward. So I don't think that worn trigger parts are a problem. A bump fire is the only thing I can think of as a truely likely candidate.

 

[El Rojo]

I double fire my M1A all the time when trying to shoot groups with it from a bench. Not quite sure how I manage it yet, but it happens. Weird, scary, and cool all at the same time.

 

[ny32182]

ER, sounds like something is not right...

 

[Bartholomew Roberts]

Yes, you've got the function check down. If it passes that, then your fire control group is good.

A slamfire is possible if the primer is seated too high. What type of ammo were you using?

Since it only happened once, I am kind of leaning towards an accidental bumpfire if the FCG is solid.

 

[strambo]

If you were crankin' rounds off that fast...my vote is "bump fire" as well. Now if you could get it to reliably double...that would be cool.

 

[ny32182]

Ammo was Georgia Arms canned heat 55gr FMJ (their plinking reloads). I have run thousands of rounds of this ammo; never a problem. Maybe it was a soft or incorrectly seated primer on one round. Or an accidental bump fire.

The rifle looks solid to me. I'm going to call it a bump fire and stop worrying.

 

[Darkside]

You just gotta get out and try to get it to do it some more. You can say it is "safety research".... That kind of "Research" might take a couple thousand rounds or so.

You might even be able to get some sort of Government grant to help finance the "Research"

Good luck

Darkside

 

[Dave R]

Sound like an unintentional bump to me. How light is your trigger?

 

[geekWithA.45]

El Rojo: re: your M1A doubling:

The most frequent cause of this is an (intentionally or unintentionally) lubricated trigger group. It's intended to work bone dry. Check to see if that's a problem.

Failing that, check for worn parts. Fortunately, M1A triggers are wicked easy to replace.

 

[Sunray]

"...Not quite sure how I manage it yet..." I know, I know. You're not following through on your trigger pull. You release the trigger before the rifle is finished firing the shot and you bump the trigger again in recoil. This is common when less experienced guys shoot semi's off a bench. ttbadboy's, ammo wasting shooting, firing as fast as he could, is very likely the same thing.
The only other time it could happen is if the trigger pin comes loose. Had a very senior and experienced Cadet have this happen to him on a CF range one time. The C1A1 fired two shots and jammed. I had a hard time keeping a straight face when I asked him why he did it.

 

[El Rojo]

I agree with Sunray, I don't think it is the gun, I think it is me. It has only happened when I was shooting off of a table or bench for groups. Never had a problem when shooting national match. I think it is from me squeezing the trigger just right and not having a solid grip on the gun. The gun recoils and my finger pulls the trigger again.

 

[ny32182]

Will try to make it double again next time I take it out, but I'm not holding my breath.

A government grant for some "safety research" would be great.

 

[Stinkyshoe]

ttbadboy,
Do you feel there is an advantage to having the ultra lite barrel as compared to the M4 or HBar 16? Do you prefer and A3 or A4 version?

I would say that it could be the primary sear is worn some, causing the hammer to slip off the sear because there isn't adaquate sear and hammer engagement before the disconnect has done its job. You could take some off the front pad of the disconnect and have a more positive disconnect hammer engagement. It doesn't sound really frequent, so who knows what it might be. Just make sure that you don't have something that does it enough to qualify it as a machine gun.

Well anyway, happy shooting all.
Ss