FYI: I've sent these questions on to Wolff technical support too.
A few months ago I bought some +5 magazine springs for my Kahr PM9. I installed them in both the 6 and 7 round magazines. They seemed to work okay initially but admittedly I don't shoot this gun all that often. This last weekend I experienced a problem with both magazines where the first round wouldn't feed. This caused the slide to remain locked back after the gun was fired once. Obviously I was starting with a fully loaded gun and a topped off magazine.
If I starved each magazine by one round they seemed to work okay as long as I was at least one round less than the maximum the gun would hold. Note: By comparison I have one factory original 6-round magazine that functions reliably with the gun fully loaded with 7 rounds.
So my questions are?: Are the +5 pound magazines too much for this subcompact? Should I convert back to the OEM springs?"