double feed

[Beretta Lover]

I was shooting an XM177E2 clone (colt 11.5 in shorty with a cigar flash hider)with a new NHM manf 20 rounder from the bench and I got consistent double feeds with the first few rounds.

When I stood up and shot on my hind legs the problem went away. I might have been doing the maazine supprted firing position, so maybe this induced it, but I really dont remember laying on the mag.

ANy ideas what can cause double feeds? my guess is

1. Using the mag as a monopod (definitley an army no no but always practiced)

2. feed lips cracked or spread out

3. Mag catch gunked up somehow

this lower is new (DPMS, the upper os a colt) , but I have shot the rifle before with this upper. I didnt have a bunch of mags or enough time to do any testing at the range

I havent seen this since I was shooting an M16A1 as a boy soldier in the eighties and we had a bunch of dubious mags (they were so old they looked chromed)

[mpeltier]

When I stood up and shot on my hind legs the problem went away.

Are you a Centaur??????

Just kidding, Mags would be my guess.

[Beretta Lover]

half centaur on my mother's side

[BayouSlide]

Spread feed lips have caused this for me in the past.

Curtis

[kellyn]

Double feeds are usually magazine related.

[TRUBL]

Double Feeds are normally......OPERATOR ERROR!!! period.

An AR15 magazine can not....on it's own, double feed (99.9999999% correct)

Only one round is availible to the bolt face to be pushed on at the time.

Thats not to say that the root of your problem is magazine or firearm related......just not the double feed thing.

Not trying to be a smart ass here.....letting you know that when you get this type of jam, you've gone too far. You've probably shot a round, the rifle cycled, you pulled the trigger...it went click....and you pulled the charge handle back to try to manually charge the weapon, the bolt doesn't go forward, THEN....you looked to see what the problem is.

What I am getting at is....when you pull the trigger and the rifle goes click....STOP!!!....LOOK!!! Before you do anything else. You will probably see a round that hung up on it's way into the chamber and the bolt is not 100% closed. Determine where that point is....and then we can help to tell if it is a magazine issue or a barrel or a chamber or an upper issue. As a rule anyways.

You do mention that this happens when benching the rifle.....could be that you are 'cocking' the magazine in the mag well, so that the is hitting the upper and not the feed lips. Bet you have bullets pushed back in to the case and all too

This could be happening due to a bad magazine (yes, even new!!), a bad magazine catch, magazine catch opening open out of spec or a magazine well out of spec (probably not the lst 2, but it has happened.)

Try another magazine....one you've used before, one that is known to work....see where that gets ya.

My best guess is that it's a magazine problem.

[jaredr]

Double Feeds are normally......OPERATOR ERROR!!! period.

An AR15 magazine can not....on it's own, double feed (99.9999999% correct)

/snip/

Try another magazine....one you've used before, one that is known to work....see where that gets ya.

My best guess is that it's a magazine problem.

respectfully disagree with your first comment, do agree with your last. the explanations i've received from a several instructors state that double-feeds are always caused by a poor magazine. specifically, weak or out of spec magazine feed lips are releasing a round when the bolt carrier travels to the rear during the ejection cycle. at that point there is a loose round effectively sitting on top of the magazine (having popped out of the feed lips) and the bolt carrier then travels forward and strips a second round from the magazine. the double feed occurs when the bolt moves to the front, attempting to stuff both rounds into the chamber.

a good way to test whether you've got a good magazine is to load 15 rounds or so into the magazine, hold it in one hand and give the bottom of the magazine a swift smack upwards with the palm of your other hand. if rounds fly out of the top, then you've got a bad mag.

-jared

[TRUBL]

Thats ok Jared....you can disagree, once you understand the workings of the AR15 and their magazines, you'll understand that you are incorrect and the instructors that say that are incorrect as well.

There was a topic on just this a while back.....the true meaning of a double feed is having 2 rounds come out of the magazine at once. I won't say that it is impossible, how ever it is HIGHLEY unlikely. Actually, what peole are calling a double feed is an incorrect statement of an action that the operator is doing.

The rifle jams up for what ever reason and the your first thought is to "charge" the weapon.....which is the LAST thing you want to do in just about any situation. First this is to STOP....LOOK. Top instructors will tell you that, so will the top shooters. What you do next will either save the day, or cause lots of pain.

FYI....the situation you've discribed is about the ONLY way an AR15 can double feed and that is rare.....hence my 99.99999% comment.

[jaredr]

i'll see your zen mastership and raise with a pair of top instructors:sight:

skipping over the condescending BS about "once you understand the true workings of an ar, yadda yadda yadda" sounds like your principal bone of contention is what constitutes a double-feed malfunction. you've indicated that the "true meaning" of a double-feed is the magazine "feeding" (?) two rounds at once. not sure where you get that, my understanding is that this term is used to describe the condition which results from the bolt attempting to chamber two rounds, which typically occurs when magazine failure releases a round into the ejection port prior to a round being stripped out by the bolt during the normal chambering cycle.

sounds like you're implying that this condition can also be created by operator error imploying immediate action to a rifle which has experienced a failure to extract? no disagreement, that creates a problem, but then the discussion probably deteriorates into armchair commando territory where we argue about immediate then remedial action protocol whereas others will advocate an inspection and diagnostic approach. that's already been discussed roughly a million times, no intention of bringing it up again as it seems we've all got our own firmly held opinions here.

to be clear, for anyone else who was reading the thread way back when the OP had asked why his rifle was experiencing double-feed malfunctions - my comment is that these malfunctions are always magazine related, so before "tuning" any other aspect of the rifle, would suggest you just try a different mag.

[TRUBL]

Hmmm...arm chair commando? Have I gone this far in the industry to be called that???? Or maybe.....you've just insulted me.

So before the mod's close this down. You may apologize at any time.

All I am saying is that waht MOST people consider a double feed is NOT a double feed at all, they just call it that.....more often, it is meerly an operator error in that they've re-charged the weapon when the gun went click.....before looking into what happened. Do double feeds happen? Oh yes....not at all a common place malfunction.

[jaredr]

So before the mod's close this down. You may apologize at any time.

One of the things I do really like about this forum is it's a great place to actually learn new stuff. conversations are generally civil, and while people may hold their opinions with passion, there's usually oppty for reasonable discourse without some of the patronizing demeanor that most people would never adopt in a face to face discussion. unfortunately, that's not always the case.

trueblue - you've indicated that you're a "firearms designer....and user and trainer" and that "most likely the weapons use in 3 gun have enhancements that you've designed." No problem, i've been given some different information from paul howe, kyle lamb, and pat rogers. i'll disagree with you and leave you to your own opinions on the subject. you can choose to promote those opinions in whatever manner you feel is appropriate.

i think we're done here.... i'll unsubscribe so you may continue you on as you wish.

Edited June 10, 2010 by jaredr

[kellyn]

You guys realize you are getting nasty over the definition of double feeds?

Trubl, I understand what you are writing and certainly defer to your vast experience (and I mean that, no joke) but I just had what I thought was a double feed on Sunday without me doing anything to the rifle other than shooting it. I believe the mag lips let 2 rounds slip causing a malfunction as there is only room enough for one. I was shooting along in a drill, the rifle went click, I looked at the receiver and observed a "double feed" (two rounds out of the magazine being pushed by the bolt, on top of each other and the top one farther along into the chamber area). I executed an amazing Kyle Lamb style clearance and got back to shooting i.e. lock bolt to the rear, remove mag, finger bang obstruction, cycle bolt carrier 2X, reinster mag, charge weapon, keep shooting.

Is that not a double feed? If not, what is it? While I agree that operators cause many a double feed, the operator did not cause it in this instance.

[mpeltier]

The few times I have witnessed a true double feed while R.o ing it was certainly not the result of any remedial or imediate action on the shooters behalf. Bad magazine was always the culprit. The last one I saw was a P-mag that had a 1/2" split right down the spine. I have on several instances watched a shooter have a failure to extract, try to clear it like a double feed and end up making things worse. And then they go on to call it a double feed...

[cas]

Most that I see are one base over bolt. That's not the shooter.

[Alaskapopo]

I was shooting an XM177E2 clone (colt 11.5 in shorty with a cigar flash hider)with a new NHM manf 20 rounder from the bench and I got consistent double feeds with the first few rounds.

When I stood up and shot on my hind legs the problem went away. I might have been doing the maazine supprted firing position, so maybe this induced it, but I really dont remember laying on the mag.

ANy ideas what can cause double feeds? my guess is

1. Using the mag as a monopod (definitley an army no no but always practiced)

2. feed lips cracked or spread out

3. Mag catch gunked up somehow

this lower is new (DPMS, the upper os a colt) , but I have shot the rifle before with this upper. I didnt have a bunch of mags or enough time to do any testing at the range

I havent seen this since I was shooting an M16A1 as a boy soldier in the eighties and we had a bunch of dubious mags (they were so old they looked chromed)

Way back 10 years ago I took a class from Bennie Cooley and I learned about using the magazine as a mono pod. I have never had a malfunction doing this. I think this must be myth. (using the mag as a mono pod will cause a malfunction) I have never seen it happen at that was about 10 years ago I started.

Pat