CO2 BB Gun- Pounds, Joules and FPS?

the 6 poulds he could have been talking about FT/LB which is a unit of measurment for air weapons 6 being the legal limit for pistols so doubt a BB pistol is the legal limit. as for conversion into FPS it depends on the weight of the ammo used, if you search around the are conversion charts on the internet. and joules is a more commonly used power measurment there are also conversion tables on the internet