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View Full Version : Doublefeeds on a LMT AR-15 Carbine


FlyingPen
04-22-2008, 10:25 PM
Only about 300-400 rounds through it and I've had about 3 double feeds. It's an LMT 14.5" + Vortex upper with a Mega lower, LMT BCG.

I thought it may be the magazines but it's happened on both a C-products 10 rounder and a Promag 10/20.

I'm using a 9mm buffer, could this be the potential cause of it? I don't have a regular carbine buffer to test it out. The other possibilities I guess could be magazine follower or just part of break in...

My suspicions are on the buffer though, any thoughts?

JPglee1
04-22-2008, 10:27 PM
Try adding an o-ring to your extractor, make sure the ejector spring is working and in good order...

A lot of time the doubling happens from an improper extraction, or so Ive read.

Also Ive seen it happen from a gas key coming loose, causing short strokes on the eject/feed cycle.

Good luck.

J

FlyingPen
04-22-2008, 10:31 PM
It actually ejects the spent case just fine..Hm.

JPglee1
04-22-2008, 10:32 PM
Well Im not an AR expert, I just shoot one :D

Good luck with your quest. Might wanna check out www.ar15.com

J

ar15barrels
04-22-2008, 11:01 PM
How far out of the gun does the ejected brass fly when it does make it out of the gun?

And it's not a double feed because one of the cases has been fired.
It's a failure to eject.
A double feed would involve two live rounds and would certainly be magazine related.

FlyingPen
04-22-2008, 11:09 PM
It flies pretty far, sometimes beyond the next booth.

Okay, I think that's what I meant to say, it's two live rounds jamming up on each other trying to get in.

After I fire, spent case is sent flying, then the bolt comes back trying to strip the round but it stops. Okay, now that I think about it more closely, it might be a failure to feed. Not a double feed.

Then it seems it's either the buffer is too heavy or my gas system is loose or messed up?

ar15barrels
04-22-2008, 11:14 PM
It flies pretty far, sometimes beyond the next booth.

This is NOT a distance.
If you are at an indoor range and it's hitting a booth, take it outside and fire it.
Measure where the brass first hits the ground.

I could say that I had a huge cock because it sticks out of the end of my hand when limp.
If you did not know that my hand was 3" across, you might be impressed.

Real numbers please, not subjective measurements. ;)

Also, what direction does the brass eject?
Think about a clock.
Muzzle pointed downrange is 12:00 and ejection port faces 3:00.
Where is the brass landing?

aplinker
04-22-2008, 11:15 PM
Try swapping mags. If it's the mag, replace the follower with a Magpul.

FlyingPen
04-22-2008, 11:18 PM
Unfortunately, I don't have access to an outdoor range here in San Diego so I can't tell you exactly where the brass is landing as it ricochets off of the walls. Next time I go, I'll try firing the rifle and watching for how the brass is being ejected.

I'll try replacing the followers and the buffer. They're pretty cheap anyways. If it still happens at that point, I guess the next thing to move onto is the extractor or the gas system.

ar15barrels
04-22-2008, 11:21 PM
Unfortunately, I don't have access to an outdoor range here in San Diego so I can't tell you exactly where the brass is landing as it ricochets off of the walls.

This information is critical to proper troubleshooting.
Otherwise, start swapping parts.

Does the gun lock open on the last shot EVERY time?
Does it lock on the face of the lugs or on the front edge of the carrier?

FlyingPen
04-22-2008, 11:26 PM
The gun does lock open every time on the last shot.

It locks on the face of the lugs if what you mean is that it locks on the bolt catch.

JPglee1
04-22-2008, 11:29 PM
I could say that I had a huge cock because it sticks out of the end of my hand when limp.
If you did not know that my hand was 3" across, you might be impressed.
?

http://i186.photobucket.com/albums/x126/jaynesblogtemplates/man_with_a_very_big_cock.jpg

LMAO.... only on Calguns and only from Randall hahaha....


J

ar15barrels
04-22-2008, 11:30 PM
It locks on the face of the lugs if what you mean is that it locks on the bolt catch.

Are you sure it's locking on the face of the lugs everytime?
You might not realize it sometimes locks on the carrier.
This causes a failure to feed when you switch mags with the bolt locked back in that fashion and try to charge the rifle by releasing the bolt catch.

FlyingPen
04-22-2008, 11:32 PM
Ok, I'll have to double check, I just assumed it was locking on the bolt catch as I when I switch magazines, I have to release the bolt catch and nothing else in order to strip the first round of the new mag.

m24armorer
04-22-2008, 11:37 PM
It might be only the size of a pencil, but it's 12 feet long.........

And if I fold it enough times, it's huge.

ar15barrels
04-22-2008, 11:39 PM
http://i186.photobucket.com/albums/x126/jaynesblogtemplates/man_with_a_very_big_cock.jpg

LMAO.... only on Calguns and only from Randall hahaha....

You have a dirty mind.
Here is the cock I was talking about...

http://www.pet-estore.co.uk/ekmps/shops/lemonoo7/images/rubber_chicken.jpg

m24armorer
04-22-2008, 11:46 PM
Thats not a cock, it's a pecker. And it won't trip the bolt catch.