Ever see this kind of FTF in an AR?


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WolfMansDad
April 24, 2007, 01:52 PM
Last weekend we went shooting a pinned mag AR, where the magazine is fixed to make it legal in California, and it was failing to feed a lot. Rounds would strip out of the magazine, but the bullet would get wedged in the feed ramp and stop. If we pulled the charging handle back again and "let fly," the bolt would slam into the jammed round, forcing it past the ramp and into the chamber. If we then ejected the unfired round, there were two deep gouges on either side of the bullet where it had caught on the locking lugs. The bullet was actually slipping between the locking lugs and getting pinched (or bound) there.

Any ideas on what could be causing this or how to fix it? The upper was a CMMG government profile 20", and the magazine was a bushmaster ten-rounder that looks like a twenty-rounder. Lower was a double star.

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Bartholomew Roberts
April 24, 2007, 01:57 PM
Sounds like the magazine follower is nose-diving or the magazine spring isn't fast enough to push the round all the way into position by the time the bolt comes back.

I'd also check the feed ramps. Sometimes if you use an M4 lower with feed ramps and a standard barrel with no extended feed ramp cuts, you can create an obstruction there; but that should be obvious just looking at it. If you don't see any problems there, it is almost certainly the magazine.

glimmerman
April 24, 2007, 01:57 PM
move out of comifornia so u dont have to deal with the pinned mag. ( sorry i had to say it. lol)

ec-10
April 24, 2007, 04:39 PM
That is the exact same problem I have with my Kel-Tec SU-16A. That is to say that when it actually does extract rounds the next round tends to get wedged in the feed ramp.

I'll take a look at my magazines to see if they might be causing the problem. Then, once I get the FTE problem handled it should be ready for the gun show. :banghead:

Avenger29
April 24, 2007, 05:16 PM
move out of comifornia so u dont have to deal with the pinned mag. ( sorry i had to say it. lol)

Ya know, even through I don't live in Kali and absolutely hate it, I am getting very tired of seeing "Move out of ************" replies to every question dealing with the PRK.

Bob R
April 24, 2007, 05:42 PM
even through I don't live in Kali

with the PRK

I am getting very tired of seeing "Move out of ************"

I know what you mean. Like people who feel the need to replace the "C" with a "K", or refer to the state as the "PRK", much like a communist country. :neener: :D

bob

WolfMansDad
April 24, 2007, 06:18 PM
Avenger and Bob, thanks guys! I've lived in many states, and each has its flaws. California is the best place I've lived by far, even if housing is expensive and we have to pin the magazines on our range toys. :)

Bartholomew, thanks for the advice. Change of mag might be worth a try, and we can test it with snap caps. FTF occurs with them as well. Don't even need to go to the range. I was focused on the feed ramps and locking lugs and didn't think about the magazine.

blackhawk2000
April 24, 2007, 07:44 PM
Can the ************n from the PRK please post a pic?;)

1911_Mitch
April 24, 2007, 10:11 PM
Californians have overcome the pinned mag dilema.

Change to a bullet button mag release (10 round mags only but detachable with a bullet tip) or run a Monsterman Grip with no "evil features" (PC 12276.1) and you can run detachable pre-ban mags if you have them.

WolfMansDad
April 25, 2007, 01:38 AM
Can the ************n from the PRK please post a pic?

http://www.thehighroad.org/attachment.php?attachmentid=57135&stc=1&d=1177478790

Excuse the crappy camera. The round is a dummy, no powder or primer, but this is what happens at the range as well. Behavior is the same with different mags.

WolfMansDad
April 25, 2007, 01:48 AM
A close up of the bullet (again a dummy round), showing one of the gouges the locking lugs make. The cut is near the tip, and the light is catching it in this picture. There is another on the other side.

Should the feed ramps/locking lugs put these kinds of cuts on the bullet? Somehow I don't think so.

http://www.thehighroad.org/attachment.php?attachmentid=57137&stc=1&d=1177479818

blackhawk2000
May 2, 2007, 02:20 PM
Pictures aren't working for me.

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