Nikon got out of the scope making business.
Probably plenty available on the used market though.
The Monarch line is decent.
My daughter did this with her AR, 18 in barrel at 300 yards using Hornady steel match 55gn ammo.
This guy know of what he speaks.
I had a Barska spotting scope.
It was so damn blurry at 200 yards, you couldn’t see 308 size holes in plane white printer paper.
Cheap glass just plane sucks.