/sci/ - Science & Math

Bruhs. I'm an amateur at this shit. This is a paint representation of a reaction going off in a gun chamber. I read that during the ejection the bullets acts on the gun and the gun acts on the bullet, which is perfectly logical. However, the rapid expanding gas pushes on both and throughout the gas the forces mediate. I'm just not sure how. Anyway, I get confused when I'm supposed to add action/reaction forces, if I wanna do an FBD of a bullet I'm supposed to write only the reaction on the bullet without the bullet's reaction on the gas, right?

Please excuse this disturbingly retarded post, hopefully you understood what I want to understand.