50-50, probably the mag release catch but when one starts to modify the catch, he can easily go to far with the mod and then you have magazines dropping out when not wanted. I think u kinda proved that to yourself with all 7 magazines catching on the release. One could get a new mag release and test it out, as most kahrs have no issues, . Doing the followers like u did is very easy and if u screw up u just put in a new follower.

It sure would not take much in a design change for kahr to do what we have to do to our followers to even eliminate that possability of happening. The thing about the magazine catch mod is when you haveit out of the gun, "just where do u start to filer" on it. It's kinda guess work IMO.