View Full Version : Intermittent failure to feed
My new carbine build failed to feed a couple of rounds during break-in/test firing. The round was stripped form the mag but failed to chamber and ended up with a big dent just south of the case neck from one of the bolt lugs. This happened three times in 50 rounds of firing. I'm guessing it could be the carbine buffer? The rifle is a 16" M4 profile carbine barrel (Daniel Defense) with a Mega M4 upper and a matching Mega lower. Commercial stock extension with carbine buffer. Spring measures good (length), but is used. Ammo was LC M855, and the mags are 20 rnd. USGI. No other problems encountered.
What say you community?
Thomas M-4
09-26-09, 13:06
What magazines are you using I have a old brownells GI mag body made by c-products that did that to me.
Sound like a weak mag. Try a new one and report back. :)
.
Heavy Metal
09-26-09, 13:30
Define: 'stripped from the mag'.
Was the bolt behind the head of the case or was one of the lugs digging into the side of the case?
My guess is that the USGI 20 rounders are worn.
My new carbine build failed to feed a couple of rounds during break-in/test firing. The round was stripped form the mag but failed to chamber and ended up with a big dent just south of the case neck from one of the bolt lugs. This happened three times in 50 rounds of firing. I'm guessing it could be the carbine buffer? The rifle is a 16" M4 profile carbine barrel (Daniel Defense) with a Mega M4 upper and a matching Mega lower. Commercial stock extension with carbine buffer. Spring measures good (length), but is used. Ammo was LC M855, and the mags are 20 rnd. USGI. No other problems encountered.
What say you community?
Define: 'stripped from the mag'.
Was the bolt behind the head of the case or was one of the lugs digging into the side of the case?
One of the lugs was digging into the side of the case.
Heavy Metal
09-26-09, 18:48
Bolt over base malfunction.
Either a bad mag or short recoil.
Heavy Metal
09-26-09, 18:49
Who made your bolt and carrier?
RogerinTPA
09-26-09, 18:59
What magazines are you using I have a old brownells GI mag body made by c-products that did that to me.
I had some Cprods that cause a bunch of problems for me due to insufficient spring tension. I used them for a while after rebuilding them, but some still induced the occasional double feed. I finally got tired of dealing with them and threw them out.
Who made your bolt and carrier?
Bolt and carrier are USGI, so ? From what I'm reading on this and other sites seem to all point to bad mag. I have a brand new Pmag I can try, and see if I get any failures.
Heavy Metal
09-26-09, 23:39
Define USGI. Who made it and where did you get it?
the Bushmaster mag in my new rifle did the same thing out of the box. I switched to PMags and haven't had a FTF yet, then again im NOT an armed professional...
Assuming that everything was assembled properly and you weren't using garbage ammo I would say that the spring in the 20 rounder is worn. Simply try a new one of known quality and see what happens.
I got the BCG at a gun show from a guy selling a variety of Ar-15/M-16 parts. He had used and "as new" U.S Government Issue M-16 BCG's. I bought an "as new" one. The bolt is marked MP and the carrier has no markings. Both looked new. The ammo is reloaded (reclaimed) SS109 on LC brass, also bought at a gun show. I would be much more inclined to suspect the ammo than the BCG.
The ammo is reloaded (reclaimed) SS109 on LC brass, also bought at a gun show. I would be much more inclined to suspect the ammo than the BCG.
Is the ammo factory reload, or is someone just using the LC brass in their basement?
You might have dropped the mag on a hard surface feed lips down.
That peens a little case rim indent that will cause the round to either bind or top tip down as it overcomes that little lip.
So most likely it's magazine related. Take a look at the magazine's feed lips. Carefully compare to a new mag.
It could be weak spring pressure too or worst case and most unlikely short stroking from a misaligned gas block or worn or aligned gas rings.
Is the ammo factory reload, or is someone just using the LC brass in their basement?
Somewhere in between; it's from a guy who is at the local gun shows who reloads a variety of calibers. Definately not factory, but the guy loads a lot of ammo.
When I go the the range, I don't just use one mag. Rather, take several and load them up all at once so when I start shooting I can keep at it. The range I go to only allows a max of six rounds per mag (what this is supposed to accomplish, I couldn't offer a guess). Anyway, I had only three mags that day and I didn't use one of them at all (a dedicated five rounder). So it's narrowed down to two 20 round mags. They're both Simmonds Precision Products, Inc. with metal followers.
I'm going tomorrow to practice some position shooting, so I'll have a chance to try a new mag and see if I still get the failure or not.
Here is my thought on reloads. Regardless of whether they reload 100K rounds a year, they are still reloads. One should ALWAYS use factory ammo first when troubleshooting a weapon.
Somewhere in between; it's from a guy who is at the local gun shows who reloads a variety of calibers. Definately not factory, but the guy loads a lot of ammo.
When I go the the range, I don't just use one mag. Rather, take several and load them up all at once so when I start shooting I can keep at it. The range I go to only allows a max of six rounds per mag (what this is supposed to accomplish, I couldn't offer a guess). Anyway, I had only three mags that day and I didn't use one of them at all (a dedicated five rounder). So it's narrowed down to two 20 round mags. They're both Simmonds Precision Products, Inc. with metal followers.
I'm going tomorrow to practice some position shooting, so I'll have a chance to try a new mag and see if I still get the failure or not.
Thomas M-4
09-27-09, 17:31
I number my mags and keep a pen and post cards in my range bag. If I have a malfunction I right down what mag I was using , what type of malfunction and what type of ammo I was using at the time. It helps to trouble shoot the more accurate the info you have.
Use factory ammo for sure I like to if I can to use 5.56 pressure ammo for trouble shooting problems.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.