There's the Thompsons of course, and while I've never fired one, I've handled a couple. They are heavy.
I've got an HK USC which is an available gun, but they are pricey. Beretta makes their CX4 Storm in .45 ACP, but magazines are limited to 8 rounds. Feather makes a RAV45ACP and there is a MechTech conversion to make a carbine out of a 1911 or a Glock. Hipoint has long promised their carbine in .45, but that's yet to appear. And Valkyrie makes an M3A1 Grease Gun replica as well as a DeLisle Carbine replica - I really don't think either is a viable HD gun investment. There's also a .45 carbine offering from Masterpiece Arms that looks like an ergonomic nightmare.
I'm on the verge of assembling my second .45 ACP AR-15. Upper receivers are Olympic Arms and lower options include: Bazooka Brothers BAZ45 (which I'll be using for #2) that takes 30 round grease gun mags, CNC/Khalan AR45 (also takes grease gun mags), Cavalry Arms MKII lower that takes grease gun mags with a Hahn magwell block and a standard AR lower with 16 round Uzi mags modified with a magwell block welded on (which is my #1's configuration). Obviously, I wouldn't be building a second one if I didn't like the first. But it will take some effort to assemble the pieces.
For an off the shelf solution, the Beretta is probably your best choice.