This is a cool game! I like the overall tone of the game, the gameplay is great and the art is very fitting too! Nice work on that. I do like the idea that every character is literally a sentient gun, it's very funny. I'd say the large shotgun miniboss is very nice and challanging but feels so good defeating it.
To criticise a bit I'd say since the hitbox is pretty large and unforgiving, making avoiding bullets quite difficult or downright impossible at times. That strange hitbox also makes the player stuck in some narrow corridors when turning, which doesn't feel right. The final boss is a bit underwhelming too. What kind of final boss is that who just summons a minute boss and don't fight by themselves!
Anyway, this is quite a solid entry! You should be proud of yourself!