Can anyone tell me the major differences between these two models? I currently have a 4" 686-5 and am contemplating buying a 686-3. I understand that the -3 model has a hammer-mounted firing pin - is this correct? If so, are there any problems that can be expected with this configuration? How about strength? I am guessing no change there given they are both built on a (K or L?) Frame. Finally, does anyone have a 2.5" version of the 686-3 and how do you like it?