I've been testing the Reticle-Tru for a while now, and it works.
I tested at first with a simple method I use for testing many scope-mounting tools, by trying it on rifles with scopes already properly mounted and sighted-in.
Scopes that have reticles and innards set up properly will shoot groups directly in line with each other vertically when adjusted up and down. (Well, as long as the target has been leveled, and the reticle is aimed square on the target.)
In every instanceon these rifles, the Reticle-Tru showed the crosshairs to be correctly aligned.
That said, there are certain parameters:
1) As some people have already suggested, if the reticle is canted inside the scope, there can be problems. But there are problems with such scopes anyway.
2) Many factory rifles end up with the scope mounts canted slightly, for various reasons. The Reticle-Tru won't work precisely with those rifles, but it will come close.
3) You have to be able to perceive if the Reticle-Tru itself is centered. I've found some people have a hard time with this, either because their have middle-aged eyesight or somehow can't keep their eye directly aligned behind the scope and Reticle-Tru.
But in general it works really well!
