I strongly urge you to mount the scope right where it should be mounted - on the cantilever. The barrel doesn't provide the cantilever mount as a convienence, it provides it because it is the best way to keep the scope in alignment with the barrels bore. Bydrilling and tapping the receiver you aren't doing yourself any favors by mounting a scope up there because receiver does just that, it receives the shells and puts them in the barrel.

I don't want to "dis" you in anyway, but IMO a variable power scope like thatwould be one of my last choices for a slug gun. I recently set a 12 ga pump with a cantilever/3-9X scope set up. It was a factory bore sighted cantilever set up and shot well from the start - with just slight tweekingit was a bonefide killer. We were forced to use it with the 3-9X due to time restrictions but that scope is now off and will be replaced with a straight 4X (as are all my other slug guns). Whatever you do with the scope though, I rec you stay withatleast a 32mm lense size. We have been using Simmons Pro-Diamond scopes with absolutely no problems, great light gathering, and no zero-wandering.

Guess what willbe my next scope.

Use the cantilever mount, and fit your rings to your mount using an alignment dowel to make sure or a square mounting. Then just a dap of some serviceable loc-tite on the mounting screws and rings.

Some deer are gonna hate you!