1892? Then it's absolutely NOT safe to fire with .308 ammo. It's relative value is greatly reduced by the fact that it's not in its original chambering, and the fact that it's missing a mag isn't helping either. '89 mags are fairly hard to find.
And when you say that a piece of the forend is missing, I can only assume that it's been sporterized. What is puzzling, however, is that all Schmidt Rubins have one piece stocks, unless you are referring to the handguard.
My guess would be a parts gun, probably worth more if you sold the individual parts on eBay or some such. Overall, my guess is about $75-80 as you describe it.
Pictures would help.
Last edited by gyvel; March 29, 2012 at 09:25 PM.