Pat,
Although you posted this more than a month ago, it just now caught my eye. I acquired a 1937 S/42 this week and have been fine tuning it for shooting. Now and then the lock was engaging early, with rounds still in the mag. Last night I fixed the problem. The bend in the slide lock spring was such that it was slightly weak. I was able to strengthen it, without replacing the spring, but this is not always possible with springs.
For the lock to work correctly, there is a balancing act taking place. The mag spring force must be a little stronger than the slide lock spring force. If the difference is not correct, the lock will either not engage, or engage too early.
Your slide lock spring is either too strong, or the mag spring is too weak. You need to determine which one is closest to "correct" to know which one to modify or replace. To do that, you must either know, or take a guess, or replace/modify both.
If the gun is feeding reliably, the mag spring is probably O.K. Check to see if there is dirt or debris preventing the locking piece from moving up freely. You can probably feel it.
|