What parts are know to break on these 2 designs?
+++++++++++++++++ The amount of the US debt times a trillion!!!!!!!!!
Don't you know that HK weapons don't fail. Seriously I've put many many rounds through my UMP without a single failure.
They are completely different systems, so they're not really comparable. I don't have a G36 (nor an SL8, at least not until Saturday) so can't really speak about them, but a gun can't get much simpler than a UMP. It's a simple blowback system, there's just not much that can break, and there just aren't very many moving parts. The only possible things I can ever see breaking would be the firing pin and spring, recoil spring, and maybe the extractor and ejector.
so no know problems with these designs?
Early SL-8's had cracking problems but none that I am aware of with the actual G36.
HK PARTS THAT I keep FOR AN EMERGENCY
USC/UMP Cocking Handle Assembly
USC/UMP Firing Pin Assembly Complete
USC/UMP 45 40 or 9mm Extractor
..And just in case a NIB STOCK HK USC. But hey that's me. Like everyone else I have never had one fail but. I believe if something was going to fail..it would these parts.
I'm surprised your bin for glock parts is so small!
To answer your question. Nothing is "known" to break on a regular basis. Some people have had some minor problems with some things, but it's never the same thing twice. They aren't like the coil packs on late 90's Ford pickups, which are a "known" problem. There's nothing like that on the UMP or G36.