Failure to feed

Welcome to the forum! Is this a USGI inland carbine or a commercial inland carbine?did you happen to use the same magazine in both carbines when firing? Feeding problems are usually a magazine issue not a bolt problem but I could be wrong. if it were mine, I would try a few  USGI magazines to make sure that the magazines are not the problem, then I would change the recoil spring to see if that made it function any better. sometimes a weak recoil spring can fail to strip the round out of the magazine. does the bolt hang up on a round trying to feed or does it just ride completely over it and close? If it rides over it and closes, I would check the magazine retaining nubs and inspect the magazine catch because that might mean the magazine is riding too low in the receiver for the rounds to be picked up. also make sure the magazine spring is in the correct way in the magazine, a backwards magazine spring can cause all kinds of problems.hth

Edited by Jond41403 - Dec 17 2025 at 2:10pm

Did you take the known good bolt and test it in the carbine with the feeding issue? You said you put the miss-feeding bolt in the good carbine and it failed, just flip-flop the good bolt into the miss-feeder as a double-check. This will give additional credence to suspect the bolt.

is there any way you can post a picture of the bolt in question? Hey Floyd, can a bolt have burrs on it to slow its ride down the rails? I have never heard of this it's usually the rails that have the burrs. You would know out of any of us of what's probably going on

Yes it did. No issues.

Pictures

I'm no expert but the bolt ramp looks fine to me. It doesn't look worn or filed

Yes it has .U. on  the bolt. What is the meaning of .U.?

floydthecat wrote: Manufactured by Underwood, a genuine USGI bolt. It’s difficult to say what might be wrong with it. Various surfaces have to be in the right place. I have ran across an Inland bolt that had to be polished in a couple of areas to make it run. I think it’s very rare to have a problem with a USGI bolt but anything is possible. Seems to me that you have determined that bolt won’t run in two different carbines. You could send it to me and I can look at it and test it in my carbines. If it will run for me, I could swap you another bolt. If it won’t run for me, we will know it is definitely faulty. Otherwise, I suppose you need to obtain another bolt.

Can you get a better picture of this? This picture is too fuzzy to zoom it and get a closer look inside the triangle.