Canuck,
If you are serious about shooting formal BR, check what your rifle weighs without a scope/mount set up on it. The 10.5 max is what you want with a scope, that allows you to shoot in all 3 varmint classes. Subtact what your rifle weighs without the the scope from 168 oz. The difference is what the scope/mount can weigh and make class LESS one ounce. This all assumes your rifle is the 10.5 version 40XBR that Rem. made, if not you are locked into the 13.5 lb. class max.
FWIW
Steve Kostanich