When the 40S&W came out many less than bright companies just assumed you could take a 9mm and replace the barrel to make a .40. They didn't seem to understand that the .40 was a more powerul cartridge and some other changes had to be made .For the most part it needed about 3 ozs more weight in the slide .
H&K first developed a slim slide but felt it wouldn't last forever so made the standard heavier slide .I didn't know the slim slide ever reached the market.
Well I've got the heavier one and love it so I guess I'll keep it !
