Howdy! I'm a newb here, but I think I'm having the same sort of problem. When firing, or when cycling the action by hand at home, it doesn't want to fully lock into battery--reaching up with the firing hand thumb is usually enough to snap it closed, but that makes it feel like firing a single action army!
I at first thought it was the mainspring, not giving enough oomph to close the action (and it WAS weak; I compared it to gun show pistols). I've just replaced that (what a chore!) --the Wolff replacement was actually somewhat larger, but from what I can tell, my "original" spring my have been too small or weak, or possibly not even the correct spring at all!
However, after all that, it still doesn't want to lock into battery. It's clean, but after reading this I'm thinking maybe a good GI scrubdown is in order. Might the s-link be bad? Are there other issues that may contribute to this problem? I don't remember it doing this when I first bought it about ten years ago, but between deployments and training, it doesn't get fired nearly often enough. Any input would be appreciated! =)
Alex