The Chicago typewriter, the classic mobster gun (ignoring the fact mobsters actually used M1918 BARs most of the time for actual hits), and TaneRisa-chan proving that even as a gun, she protects us. Highest HP among SMGs but conversely has abysmal evade. Has a very good invul skill though, and is a solid tank overall, though she'll need a lot of repairs after every mission.

Younger sister of the Ultimate Maid, G36. Classed as an SMG for balance reasons, she's a fairly good tank with alright dodge, very high HP pool, and with an invul skill. A very good all-around tank with better buff tiles than Thompson. As far as general use shield tanks go (like say, dealing with dragoons later), she's actually pretty alright, but some future enemies will make Thompson's HP matter a bit more.

Get her mod. Please. It's broken. More info here