There's a pretty good article on steel-case .233 Remington ammo on the Cheaper Than Dirt Blog. I would just add that you probably want have a carbine buffer in the gun, as an "H" buffer or "H2" buffer may cause the action to run too sluggish with lower-powered ammo.
Sturmgewehre shoots a lot of Wolf ammo
Tula .223Rem Fail - TulAmmo steel-case ammo short-stroked one of my AR-15s
