I've played paintball roughly eight years. Four years competatively in tournaments, ranging from local tournaments, to the PSP, to the NPPL.
I would, based on my experience with paintball, return fire if fired upon by a paintball gun outside of a paintball field if i felt that I was in danger, and it wasn't some punk just trying to scare me. I will not lose my eyesight, or life, on a prank. I feel I have the knowledge and experience that I could defend myself in court, even more so with an experienced lawyer.
1) 300fps is the maximum WORLDWIDE accepted speed for safety. Many (all) guns can fire faster if you give it higher gas pressure, higher spring pressure, higher (slower) valve setting, etc.
(As a side note, I call shenanigans on whoever said they got a paintball up to 900fps. I just don't think its possible to get one past 450-500 unless... Well I don't even know how, nor will i pretend to. They just aren't made for it)
2) 300fps is the standard for safety, GIVEN THAT participants are wearing proper safety equipment, which I would not be wearing, leaving my tender, loving eyes exposed to the potential (ie : no guarantee of safety during retreat, and potential for severe physical damage, such as losing my eye)
of being destroyed.
3) Paintballs can be frozen. It leaves a small welt when it hits you if safety precautions are taken.
3a) I have no guarantee it is not frozen\altered\actually a "standard" weight paintball
3b) I have no mask, protecting my face/neck/temple/ears.
4) If the little bugger is doing it to me, he's probably going to do it to someone else. (In theory, I suppose I could come to the aid of someone
else who is being fired upon by paintball guns, seeing that PA state law says I can use force to defend someone else, if I would be justified in using it, if I was that person who I am defending)
Pick me apart, I'll only end up smarter if I get feedback...