Sorry I nead to correct a dangerous misapprehension that andrew is under.
Not quite true, the legal limit for an air rifle in the UK (not including NI) without holding a Firearms certificate is 12 foot-pounds which is a measure of force
Actually it is a torque, which leads one onto a momentum or angular momentum. Strictly you need to know the inertia and not the mass of the projectile. Momentum and energy are interchangeable given one knows the mass, or inertia. I’m not sure if the torque is in relation to the torque applied by the rifling, or if it is used to derive the momentum of the projectile itself! Anyone know the answer?
16 joules is just another equally valid way of quantifying the legal limit. It could in fact be one of two limitations.
Working with energy tends to be easier for calibration, reason being, it is cheaper to measure the muzzle velocity and weigh the recovered missile than it is to use a ballistic pendulum. If you go to the trouble of calibrating with a ballistic pendulum energy and momentum are both easy to work with.
I have in fact been hit by a pellet from a "full power" air rifle; the pellet went through my hand between the knuckles. I am under no illusion as to how powerful they are; perhaps saying just piercing the skin at 6’ was inaccurate, but not all that far off mind.
Edited by Andrew, 20 February 2006 - 08:56 PM.
