Originally Posted by JR
Nope, no such thing as a heavy slide stop lever spring.
FYI: I do not agree with your findings. I am sure your shooting style is accidently engaging the slide stop lever. When the gun is under recoil the edge of your thumb is creeping up along side and engaging it. There is a simple test you can use to verify. Remove the top end, flick the slide stop lever upward. If it springs back down into position you are good to go. It has performed its job flawlessly! Now to prove it to yourself insert a loaded magazine. You will see there is absolutely NOTHING near the slide stop that would engage it.
Odds are you recently installed an extended slide stop and the problem has sprung up like a nasty weed. The easy fix is to modify your shooting grip and adopt "high thumbs". This grip is very common among 1911 shooters. The other fix is to go back to the standard slide stop.
I never installed an extended slide stop, as I stated in the initial post.
Also as I stated in the initial post it happened about three times per mag and then stopped, when I installed a new part. I did not mention this was for several mags in a row, not just one. Therefore, I really believe it was the part and not me.
This repeated failure was the first time it happened, last time I simply replace the part at the first sign of failure. So possible in later situation my thumb has engaged. But no way in my opinion was my technique the case, when I ran a couple of mags thru the glock, being very careful to assure my thumb was down and had about three lockbacks per mag and then it stopped immediately and for several thousand rounds after I replaced part.
I have tested the spring tension, as you suggested and it does get weaker with use and this is when problems happen. But the spring would have passed your test, when I was having the bunch of lockbacks. It is difficult to tell exactly, when the spring is weak enough for this problem to occur. This makes preventive maintanence difficult.
Appreciate your response but we will have to agree to disagree on this one, at least in regard to the cause of my initial problems.