Installed the KNS bolt catch pin and used it for one outing. The "E-Clip" seems to be holding, though it is very tiny. Pin is a little undersized, so it does not fit tightly, which I don't think is a problem. I suppose the hole in the receiver could potentially become "egged," just from the pin banging around as the bolt is caught and released thousands of times. I'm going to keep using the KNS pin, as I really don't like the extended bolt release hanging out there when I'm not using the Shrike upper.