Bulkheads and windows would be pressurized compared to the outside, so armor piercing rounds and high caliber weapons would be detrimental to both sides. Flamethrowers are out (unless you're crazy... and some people are). But at the same time, people still need killin'. I tried (and failed) to find any information about weapons aboard submarines or spacecraft, which is the style of living I envision these people having.
For reference: in this world biological warfare has rendered the outside dangerous, so air filters on everyone is just a fact of daily life. Are there substances that easily bypass conventional filtration systems? Are there records of weapons designed to kill/incapacitate people in biohazard gear, even circa WWI?