I was there when Ron got shot. We think it was a G&G "Extreme" pistol that was used, they shoot at 450...
It's gonna sting, even at 350. I've been on the Zombie side, and it's just the nature of the game.
If you drop the FPS too far, few people will have an "indoor gun" that'll chrono.
Zombies, wear thick clothing and a chest protector and cup.