CJW Posted June 23, 2015 Share Posted June 23, 2015 Doing a little practice at the range this weekend and had one odd malfunction with an M2. A round got stuck part way out of the magazine and apparently under upwards pressure form the carrier. So, this was not the last round in the magazine and I had no other indications of a weak magazine spring. Also, I am pretty sure this is not a carrier spring issue (had that before, know what it looks like, and the spring was replaced fairly recently). The odd part was the upwards pressure on the shell; my understanding is that the carrier should not release until the fully released round hits the release at the back of the loading port, so I am not sure how the carrier could be pressing up on a partially released shell. It only happened once in about 175 rounds, but it was a bear to clear; as I recall I ended up pushing it back into the tube until it felt like the upwards pressure let off, then pulled it out clear onto the carrier and I could finish cycling it. That would be a killer of a stoppage if it happened on the clock. Any ideas? Link to comment Share on other sites More sharing options...
Jadeslade Posted June 23, 2015 Share Posted June 23, 2015 The carrier spring pushes the lifter down. There is a little pressure upwards from the spring, but the bolt going back is what lifts the shell up. Don't understand your malfunction. Sounds like magazine spring is too long, the shell catch isn't catching, or it's all just dirty and misaligned. Picture would be helpful. Link to comment Share on other sites More sharing options...
MarkCO Posted June 23, 2015 Share Posted June 23, 2015 Shell catch over-tuned and then (or just) worn out. Link to comment Share on other sites More sharing options...
CJW Posted June 24, 2015 Author Share Posted June 24, 2015 Out of curiosity, how does a worn shell catch lead to this? I am not doubting the explanation; I just want to understand what's going on mechanically. Link to comment Share on other sites More sharing options...
MarkCO Posted June 24, 2015 Share Posted June 24, 2015 Rounded over, not enough angle, too floppy (especially if the notches are cut in the sides). I had one I re-bent and filed back squared, lasted for about 1K, then it started again. I just changed out with a new one. Link to comment Share on other sites More sharing options...
openclassterror Posted June 24, 2015 Share Posted June 24, 2015 Normally the shell catch prevents the lifter from lifting until the shell depresses the tail of the shell catch as it pops back out of the magazine tube. What is likely happening is that the shell catch isn't holding the lifter down, and the lifter is slipping off and starting to move upward before the shell is all the way out of the magazine tube. This usually indicated a bent catch (over-tuned), or a rounded-over shelf on the shell catch where the lifter is supposed to stay until the shell pushes the catch aside. If you retract the bolt with the magazine empty after hitting the shell release button and then ease it forward, you can see the lifter just start to move upward when the bolt locks open. If you hit the bolt release button on the outside of the receiver, you are simply pivoting the tail of the shell catch out of the lifter's way ( which is what the shell would be doing if it just came out of the mag tube) allowing the lifter to move upward so the bolt can close. What you are describing is the lifter lifting before the shell hits the tail of the shell catch. A new shell catch is likely the solution here. Link to comment Share on other sites More sharing options...
CJW Posted June 25, 2015 Author Share Posted June 25, 2015 Tom, thanks—that's what I was missing. I did not get the role the shell catch plays in holding down the lifter; I thought it was more of a mechanical linkage back by the carrier release lever, but it makes sense now. Yes, this is a tuned (bent not cut) shell catch with a few thousand rounds past it, so it wearing out seems like a good possibility. Thanks for the info, gentlemen. Getting ready for Nordic this weekend and I guess I will be de-bending the shell catch a bit... Link to comment Share on other sites More sharing options...
BradfromND Posted June 25, 2015 Share Posted June 25, 2015 I've got an extra shell catch I can bring with me to the match. If you don't get it fixed, send me a pm and we can meet up. I was bringing it anyway in case mine fails but I just put together a backup gun last night so I should be set regardless. Link to comment Share on other sites More sharing options...
CJW Posted June 25, 2015 Author Share Posted June 25, 2015 I've got an extra shell catch I can bring with me to the match. If you don't get it fixed, send me a pm and we can meet up. I was bringing it anyway in case mine fails but I just put together a backup gun last night so I should be set regardless. Thanks! I am hoping we have it covered, but I always appreciate the generosity of fellow 3-gunners. Link to comment Share on other sites More sharing options...
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