RE: .22 hornet
K Hornet moves the shoulder foreward, and has more capacity. That means more velocity with a bit more powder used.
You just get your Hornet rechambered for K Hornet, fire std. Hornet loads in it, and reload the fired brass with K Hornet dies.
I've thought it would be nice to have a K Hornet necked to 5mm, but i guess my wildcatting days are over......
Drilling Man