Courtesy of HKPRO:
"What were the changes H&K made to USP over the years?"
Originally Posted by Henry's Dad
Have USPs gone through "gen" upgrades (or downgrades, depending on your point of view
) the way Glock has?
Any parts compatability issues between USPs from the '90s and ones made today?
Any issues with used USPs in general that a buyer should be aware of? Were there "bad" years or a bad string of years?
1993: Original USP9 and .40.
1994: Reduced the slide weight by 1.1 oz.
1994-95: Change to a polygonal rifled barrel (Prior barrels were standard land and groove)
1994-95: Change trigger transfer bar.
1994-95: Change recoil guide rod to a "captured spring version".
1995: Change trigger mechanism.
1995-96: Add rubber spur to hammer.
1995-96: Change angle on slide lock.
2000: Add locking feature to hammer strut support.
2001: Converted captive recoil spring retainer from c-clip to machined end on USP Compacts.