Like I said earlier, my problem was that both magazines developed the same problem. Both were fairly new. Neither had been dissembled and cleaned. My problem was a result of the magazine follower NOT rising to the top of the magazine completely. The slide would not lock back on an empty magazine. Once I took it apart and cleaned it, I have not had any further problems. Yes, I did stretch the spring a bit, not much. Most of what I did was clean and spray some lube in the mag well. I no longer have problems with the follower failing to slide to the top of the mag opening. Perhaps when they are new, they aren't worn enough on the sides to slide up with out resistance. Put some lube on the inside of the mag and the follower will have less friction.

I doubt you will find a problem with the recoil spring that would result in this failure.