Trigger guard is different to accomodate different method for adjusting speed valve. Should be net zero effect on the actual grip. They reduced the size of the brass speed valve and put a thread in the trigger guard for the screw, rather than v1 bore in trigger guard for the larger brass speed valve with screw built in. Only possibility is that there is a counterbore in the handgrip if the V1 speed valve protrudes into the wood, can't remember. V1 grip will fit V3 but maybe only maybe v3 won't fit V1 (until you open up the adjusting hole to accomodate the speed valve, how easy depends on skill level). Not going to take any of mine apart. Please search for pictures if this is insufficient information.
