The rules for conservation of momentum (energy) is based on velocity and mass (energy = mass x velocity). The 0.20 g BB is used as a baseline reference to determine momentum. If you know what the round's mass is, then conservation of momentum will pretty much dictate what the velocity must be.
In Canada, the momentum limit was determined by the RCMP, and enforced by the CBSA (more or less). The RCMP's determination is based on the energy requirements to break skin, which is about 1.5 Joules. Therefore, working backwards and solving for velocity, this is where the 400 fps limit comes from (based on a 0.20 g BB). Increasing velocity with a 0.20 round, or increasing BB weight with a 400 fps limit, will result in the energy value increasing above the "skin break" threshold (i.e., greater than 1.5 J).
Downgrade your spring to a s110 or s120 for safety reasons. If the field is allowing hot guns on, and this is how they are resolving the 400 fps limit, then they weren't paying attention to grade 11 physics.
VFC SCAR-L - VFC SCAR SSR - KJW Hi-Capa 5.1 - CAW M79
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Originally Posted by kalnaren
Stalker stays where he is.
His BB's fly across the country to hit their target.