What are the most interesting platforms for semi auto pistol caliber carbines?

Especially 9mm, 40 S&W, and 45acp. Uzi, Beretta CX4, and Thompson come to mind but what makes the most sense. AR platform in pistol cal worth considering? Can it withstand 45acp? Why does no one make one in 45acp except Olympic arms? I don't usually ask questions but this project seems appealing to me and I'd like the benefit of others knowledge and opinions.