I noticed that with my styer M40 and HK usp40 after getting the standard cap mags for them they do somthing neat. both guns when you seat a loaded full cap mag in it with a firm tap the slide closes automaticaly chambering the first round. I am sure that the beretta M9 also does this too, does any other guns do this with proper mags? and I checked with 10 rounders and the trick doesnt work on them. any one know why the guns do this with standard mags and not the 10 rds?