rusty has a leaf spring, tire hammer has a coil spring, what handles the rebound on an air hammer ?

The compressibility of the air acts as a spring.

Thanks.

i figured as much , so it might be a little hard on the cylinder seals and thus the life of the expensive cylinder.

The Anyangs run for years and years with little trouble!  Much more durable than hammers that use steel springs!  Though most of those work long and hard as well!  It is easy enough to replace springs too... just a little scary when they break!