This is a necropost BUT figured I'd sharethis as I referenced this site during my odyssey for an HK11. No benefit other than look for the 21e.
Here are some pics if it might be helpful.
http://img381.imageshack.us/my.php?i...1010605yz1.jpg
http://img125.imageshack.us/my.php?i...1010606uv3.jpg
http://img403.imageshack.us/my.php?i...1010611lb6.jpg
Mechbox is being re-worked. Started life as a TM G3SG1. CA metal body, custom steel shroud. Salvaged ECHO 1 outer barrel from a SPR Mk12 and bipod from the SG1. Cocking tube handle still functional although tube is welded to shroud. Collar is PVC and steel and has a spring loaded real steel HK21e carry handle. Barrel release handle is also real steel HK21. Stock is a MSG90. Internals are Systema torque ups, M110, with Area 1000 cylinder and TM piston. EG1000 motor. Havent chronoe'd it yet but estimate 350-60 with 0.2's.
More Pics here if interested:
http://neasg.org/forums/showthread.p...439#post178439