Based on Smokpole and MattX recommendations on lens size and magnification, I purchased an Athlon Optics Talos 20-60x80. Picked this one because Midway had it on sale and based on an on-line reviewer’s opinion it was the best low-budget spotting scope. Today I took it out to the range (overcast conditions): excellent at 100y, very good at 200 yds on paper targets. A buddy was shooting his .308 at 500 yards at steel plates - I was easily able to spot for him at this distance on fresh white paint - but pretty sure it would have been hard to impossible if it was a paper target and had discern any hits in the black. At 500 yards I didn't have it dialed all the way to 60x but a little less so as to better see the dirt fly early on in his sighting-in.

I’d recommend this spotting scope for usual carbine distances if you’re on a budget.

Thanks