Hey guys,
I have an LMT trigger group that I took out of my wife's M4 and put in my new DM bastard build. Before I swapped it we were noting a very slow reset after rounds fired. I took it down to ensure that is was assembled correctly and it was, I put it in my other build and there were times that it totally failed to reset and I had to physically move the trigger forward. I was thinking that the hammer spring might be weak, but I can't find a spare right now. Are there any other places I should be looking for problems?
Check your trigger spring, since that's what pushes your trigger to the reset position. The disconnector spring, if weak will cause hammer follow with an occasional double (disconnect isn't going forward far enough to catch the hammer) and a weak hammer spring will generally manifest itself in weak primer strikes.
For reference, I've not had that one go out on an AR but I have had the trigger springs fail completely on a wartime P38, a postwar P1 and a Beretta 92F. All had the same symptoms of failure to reset. Also have had a very gummy trigger in a walther target pistol that was traced to the same root cause of a weak trigger return spring.
Whatever the final cause is determined to be, I strongly advise storing small springs as well as a set of gas rings for the AR. I learned a long time ago that the PITA factor is mitigated by $40 worth of spares in a baggie.
As an emergency move, you can (CAREFULLY) cold form the legs to increase spring tension. This is not recommended in a SHTF piece for obvious reasons. You can also learn the art of cold forming springs from music wire. Its not as hard as it sounds and can save you money and irritation when a spring takes a dump, particularly on some of the long out of production WW2 collector guns. Don't know if you collect, but try finding a cocking lever spring for a Sauer 38H sometime and you'll know what I mean. Numrich used to carry repros but they're long gone now.....
Good luck,
Grumpy
PS - I would also suggest you check for cracks in the spring. The common factor I didn't spell out up above is that the P38/P1/92F all use a torsion type spring and each one of them cracked (not the leg, the "wound" part of the spring). If one or the other of the two wound portions of your trigger spring has a hairline crack, you will lose tension on that leg and only one leg will be pushing, thus weak reset. No way to fix that with cold forming, just replace asap.
