Mr. Camp is likely correct. You are probably not releasing the trigger to reset. You can decrease the reset distance on a Mark II hi-power easily by shortening the trigger lever but it's not so easy on a Mark III, since they have the firing pin safety. The reset can still be shortened, but you would still have take-up to overcome the spring of the firing pin safety. Either get used to releasing further, shorten the trigger lever (but not TOO much...then the gun won't fire), or have a trigger overtravel stop of some sort put in.