How do I mount this scope?
 

I just got an older Bushnell scopechief iv-m, and its tube is not a cylinder, but it has a thin rail along the bottom. Regular 1" rings won't fit. What is the deal? Is this an older style of mounting technology? It's new to me.

RE: How do I mount this scope?
 

You have the old Wedge style scope that needs a two piece scope mount. The 1st is a ramp that will mount to the gun's receiver and the 2nd is a wedge that will clamp shut via Allen wrenches and grip the rail along the bottom of the scope, thus securing it to the receiver.
Those scopes aren't all nitrogen filled and may cause problems with fogging up. I suggest you get an updated scope. You'll have trouble finding the hardware to mount that scope, if you can't get it from Bushnell....