View Full Version : Buffer tube causing jams?

06-05-2012, 4:21 PM
I changed a buffer tube on my lower from a commercial spec to a mil- spec. After about 5- 7 rounds the spent shell gets left in the breach and the next round gets pushed up behind it, causing a jam.

Could it be an ejector problem or it it just a result of a shorter buffer tube being added.

06-05-2012, 4:23 PM
Shorter buffer tube? Mil-spec vs. commercial is a matter of the diameter(well, except for that little bit angled on the back of the commercial sometimes), or was there a significant difference in length between the tubes?

that guy
06-05-2012, 4:33 PM
Sounds like it could be the extractor, or extractor spring. If you can wiggle the extractor with your finger, the spring might not be strong enough.

This appears to be so common a problem that extractor spring strengthening kits with an extra little rubber doughnut to install under the extractor with the extractor spring are readily available.

06-05-2012, 4:35 PM
Yes, After I just looked at it, the mil spec is about a cm shorter. Could this really affect the momentum of the bolt enough so that the round doesn't get seated properly?

06-05-2012, 4:38 PM
Unless you didn't screw it in all the way and the buffer detent is causing a problem, I doubt it's the buffer tube.

06-05-2012, 5:02 PM
A true type 3 malfunction or 2 live rounds trying to feed at the same time is a magazine issue cause by feed lip seperation or an out of spec magazine.

06-05-2012, 5:21 PM
I doubt it is the tube.

06-05-2012, 9:18 PM
Get yourself a BCM extractor upgrade kit and report back after a range trip.

06-06-2012, 1:10 PM
I dont think it is the buffer tube or spring, but another possibility is the buffer itself. It could be out of spec. Unlikely, I know, but similar problems can happen if the buffer is out of spec. My vote though goes to the extractor. Plus if that turns out to not be a problem, you have a spare extractor.

gun toting monkeyboy
06-06-2012, 1:19 PM
I think this is just a case of Post hoc ergo propter hoc. The malfunctions you are getting sound unrelated to the change in the buffer tube, despite the fact that they started right after you did it. As the others have suggested, it sounds like an extractor issue. I would check that first and foremost. That small difference in the overall length of the buffer tube wouldn't cause anything like what you are experiencing.


06-06-2012, 1:23 PM
Double check everything is installed correctly. Try a new magazine.

06-06-2012, 2:06 PM
Dangit. I accidentally edited my previous post. I realized too late what it was doing lol Forgive me guys im still a NOOB XD.

As stated many times, the extractor definitely looks like its to blame here. I was mixing up symptoms. The bolt hold open fine at the end of a mag? If it doesn't could be a buffer out of spec. Id suggest getting a couple Pmags (theyre pretty reliable) and buying a new extractor/extractor spring. Youre gonna find having a spare extractor to be helpful even if its not the problem. Parts such as the extractor, extractor spring, and firing pin retainer pin are always helpful to have spares of.

06-06-2012, 2:26 PM
Does the spent case have any damage to the rim from the extractor? It could be over-gassed if its trying to extract the case while it's still expanded in the chamber.