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That's .22 short, I assume? .22 long is almost always supersonic.
The difference other than speed between .22 firearms and .22 air
rifles are that the bullet is c. 7 times heavier than the pellet,
so a .22 bullet carries c. 14 times the energy of a .177 pellet at
the same speed.



Don't want to appear pedantic, but isn't the formula for kinetic energy 1/2
mv2? So if v is the same for two projectiles, the energy will vary by half
the mass ratio, hence in your example it would be 3.5 times not 14 times?
Apologies if incorrect :-)

Yes, that is the formula, but you halve both weights and the ratio
remains the same.

Only varying the velocity upsets the linearity, which is why you have to
be careful with an airgun which is on the limit for power: use a lighter
pellet and the speed increases, so the kinetic energy will decrease in
direct proportion to the mass of the pellet, but it will increase in
proportion to the square of the velocity.

Overdo it, and the increase in velocity can take the kinetic energy over
that lost by reducing the pellet's weight, and render the gun illegal.

If ever the Dibble want to test your airgun, be sure to stipulate which
pellet you are using, and insist that they use the same for the test. I
wouldn't put it past some smart-alec to have a supply of very light
pellets...

--
Rusty
Open the creaking gate to make a horrid.squeak, then lower the foobar.
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