In fact............ Fired some Win factory 150s in a 91, found brass (well most), loaded 155 gr SMKs. Ugly looking, for sure. Stuff punched sub-MOA with my RPR every time. No difference vs similar (1.5 gr less powder) in LC LR (stuff I got from Postal).
HK controls are different for sure, no bolt hold-open, trigger needs work. But they are pretty ammo-flexible, and will cycle very light loads. About only way to make them fail is to run out of ammo. Some think they have alot of perceived recoil. Don't agree.