I'm sending mt TrailLite (Buckmark) barrel back... We'll see how the CS works out.
With a Red-Dot mounted on top, I had to max the windage adjustment to the left, to get the scope to hit POI. With a higher power scope mounted, I couldn't get it centered.
Looking down on the top of the barrel, the front scope-base mounting screw hole (on the top of the barrel) is drilled a tiny bit off-center.
With the 1-power magnification of the Red-Dot, no big problem.
With the 2-7-power magnification of my new scope... WAY off.
I'll let you know.
PS... Those barrels are $180 new??? I'd offer him $90 used.