I got the Vertical Retical Instrument
which turned out to be level
and should line the scope up to the bore and tell you when the rifle is uncanted in the vise
The next problem which this instrument does not solve is to make sure the reticles are level while the vertical reticle instrument tells you the rifle is uncanted and the scope is aligned with the bore. The way I did this was to put a 48" level on the fence about 20 yards away and line the horizontal reticle along it while the rifle was held thus.
Now the problem would be to duplicate the uncanted rifle and scope under field conditions. To do this I installed the Micro-Level Features
which can be calibrated while the rifle is uncanted and then you use the lights in the top that can be used while focusing on the target, red light on either end showing the most cant, yellow light showing minor canting and the green light in the top middle showing the rifle is uncanted
There is a double sided tape under the device that holds it securely to the scope and the band that is tightened down to hold it in place. It is secure but the device definitely needs to be protected from a hard knock.
It definitely works as advertised and doesn't look too out of place
The device is not really made for scopes with a large ocular but I did manage install it.