[steelcactus]

i did look up one or two this may help
http://www.onlythebestfirearms.com/umpsbr.html

http://www.lanworldinc.com/HK.html

http://www.autoweapons.com/photos08/aug/hkump.html

http://www.hdps.org/htm/2-1-1.htm
also this may help

http://www.gunbroker.com/Auction/Vie...Item=146016993

not cheep lol but can get the USC then time and paperwork and parts may save a tiny bit