I have a 17 HMR and love it. Flat, accurate and fun to shoot.

The only difference in the 17HMR and the 17HM2 is velocity and you have more bullet choices with the HMR. The HM2 uses the same 17 grn bullets used in the HMR, but it's based on a .22 long rifle Stinger round instead of the .22 mag case, so it has less velocity and energy. The 17 HMR has some 20 grn controled expansion offerings that were devoloped for a bit larger game like what you want.

Personally, if I were going to get a rifle just for dog sized game I would go with a .22mag for the extra bullet weight. Or better yet a centerfire like a .223 or something. The .17 will do it, I can't deny that. There are too many people on rimfirecentral doing it to say it doesn't work. I just think the .22 mag would be better is all. That is all I think it's better for though.

Good luck,
Paul