I'm a submissive masochist in a BDSM relationship. My Mistress wants to shoot me in the ass and back with an airsoft gun. I have safety questions

What combination of muzzle velocity and bb weight/size do i need to leave marks, have it hurt, and not break skin at a 10ft range?

This is not a shitpost, I need actual answers by the way. I'm also an emotional masochist so feel free to make of me for this.