I have this and I love it way better then benelli brand. I’m not a fan of the twist lock feature. There’s is like a AR15 style, and its 9 positions vs 3 positions.
I may be a little late on the matter but I can 100% confirm it fits on an M4. I have a M4 using S&Jhardware’s collapsible stock. I love it better then the twist lock.