I have a 17HMR, and friend who wants one asked whether you can shoot the H2 through a 17HMR rifle? I would think the extra length in front of the shorter shoulder of the H2 would be an invitation to lodging the bullet in the breech and...well, not a good thing.

Just wondering...

Likely rupture the case, or worse.

Akin to shooting a .22 rimfire in a .22 mag... don't.

Judging from the side by side picture i have seen of the 2 17's, I would say that you will have a catastrofic event. The 17HMR is based on the 22WRM and the 17HM2 is based on the CCI stinger 22LR. There is a gap for the bullet to pass from the 17HM2 fired in a 17HMR chamber that could allow the bullet to upset before reaching the throat.