can you use 17 hms or 17marh 2 for silhouette?

No. The tiny bullets go so fast hat they damage the targets. Plus, the rules specify the use of 22's to equalize the game so that your competing against another shooters ability and not having to overcome their ballistically superior rifle.

thats what i thought,thanks

The club I belong to has a special match for 17HMR folks this year, they made special targets and are shooting them out to 150 yards, I would assume this is not an original idea, check the clubs in your area.
BTW I've never heard of the two 17's you mentioned, what are they? 17hms? 17marh 2 ?

I'm pretty sure he meant 17 hmr and 17 mach 2.

Dustin