How do you unjam the H and K Usp co2 pistol?

Umarex USA makes the H&K pistol. I suggest you contact them. See the link below

See the link below

I beleive AirsoftMegastore recently got them in stock.

100-5000 depending on specifics

Try Numrich Gun Parts Corp.They have lots of parts for most any gun. Good people to deal with.