I wouldn't really worry about it anyway. There isn't much to fail in the HK USC/UMP. Most of the parts are pretty straight forward and easy to replace if need be. Not too expensive either when you consider the cost of the gun.
Most of the parts that have me worried cost $20.00 to $50.00's in price.
Firing pin, extractor, bolt bumper etc, all inexpensive parts. Unless you shoot hot reloads and your gun explodes, I'd not worry about it too much.