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Conventional guns work fine. Sure, there's recoil. But you wouldn't want to fire without bracing yourself on earth. Why would you in space?
Okay, I can picture a rare situation when two opponents in close draw and start firing unexpectedly, which could result in some macabre corpse tumbling. But I think it's maybe as likely as a rifleman hitting his brow with the recoiling scope. It happens, but not all that often.
A few larger conglomerates might develop specialized weaponry. Tazers, mazers, lazers, recoilless rifles, smart grenades, and even battlebots. But that stuff is expensive, rare, reliant on extensive infrastructure, impossible to repair, and a dead giveaway of who you work for.
The vast majority of weapons will be literally what is here today. There's tons of guns that work well enough and making new ones is expensive. Settlers can't afford more than an old AK and proven principles refined over centuries by master gun makers are still the go to option for modern militaries, aside from what they let their special commando operations field test.
Fouling might be a bigger issue when firing outside of an atmosphere. And the building materials for ammunition in space might be inferior, the production methods imprecise.
There will certainly be a wide spectrum of weapon technlogies.