SpudFiles

I know their are regulations on paintball speeds in a game, what is the limit in fps and about what pressure in a gun would that amount to with say a 4 foot barrel?

over 300 fps cam break a mask or even a rib.

Where I go paintballing the max is 285. I took my pneumatic with a chamber size of about 40 cubic inches and a 38 inch barrel that fits paintballs perfectly (it's SDR-13.5). At 65 psi the chrony said 571. Ouchies

"Over 300 can..."

Oh, like there's a magic number. There's not. Get used to it, there almost never is.

...but generaly, they restrict it to about 300 fps. You'll need to use pressures in the range of 15 psi or so to go that slow. (no math, just a geuss)

There can't be a magic number, since it depends on projectile mass (contained energy) and how hard the paintball's shell is (energy transfer). Terminal ballistics and all that jazz.
A feather going at Mach 4 (theoretically) won't break any ribs, while a bowling ball at just 10 fps will knock you down.
So, since there isn't just one standard paintball, there can't be one standard maximum speed, so a safe speed is considered (as stated before, around 300 fps).

Ok, I thought it was about 300. If I do build one I'll probably keep it down to low pressure like 20 PSI. Thanks for the help.

lo pressure is a good thing because then you can get more fills from a CO2 tank or pump faster with a hand pump