There are a number of free standing stands that allow you to spot shots from position and not have anything attached to the rifle.

An example can be found at :

http://www.ray-vin.com/

There are several examples found at the top of the page.

These are used mostly by competitiors shooting High Power Rifle and High Power Long-Range since most of this is fired with iron sights.

Be warned that seeing hits, even with very expensive scope, is problematic past 200 yards or so unless you are shooting large bullets or take some measures at the target to increase constrast of back lighting.

High Power competitors do not use the scopes to see bullet hits, they use them to observe mirage (heat waves) to determine the effect of the wind on their bullets flight path.

If you have more questions let me know, I wanted to keep this post short.

Lee