Steve: Yes, what you are saying is correct, however S&W does not recommend dry fireing. The FP spring has nothing to do with the maximum foreward travel of the fireing pin in the 15-22 with exceptions. Maximum forward FP travel is determined by the FP slot and stop pin, period..... 1) The first exception being that the Hammer spring is too weak (light) and it can not overcome the FP spring tension to drive the rebound fireing pin far enough forward into the shell and hit with impact hard enough to fire the shell.....Exception 2) the length of the FP spring is too long and was put in at S&W factory by mistake....(you won't find this), but an overly long FP spring could cause the FP to be restricted in full travel length...... This max forward FP travel is determined by the FP stop pin and slot. If it was assembled at the Factory correctly, the FP at full extension will just clear the breech face of the barrel, and leave no marking....at least this is the way it is on my 15-22, and I suspect it is purposely manufactured this way...Do Not increase the slot length on the FP. It is not needed, and has plenty of full travel to detenate the shell.....Take a look at it yourself, simply push the FP in as far as it will go and look at the FP protursion, it should be just shy of the face of the bolt, and I mean just a few thousands....Look at it under some magnification and you will see this....best regards Plum