Most scope bases, rails, etc. attach through manufacturer's installed threaded holes. Usually #6-48, but some are #8-40. You will find neither at hardware store. When I needed spares, I have included them in an order to Brownell's in USA. If you did, or hired someone to, drill and tap those holes, then could be many sizes, including various metric sizes. So I guess I am not much help - I do not know what hole size / threads per inch has been drilled and tapped in your rifle, or by whom, and I have never needed to try find a Canadian source for 6-48 or 8-40 screws, if that is what you need. A person or business that drills and taps scope base holes would have taps, etc. to check what size hole and threads per inch that you have - might even be able to figure it out by measuring the "blank" filler screws that are normally installed by firearm manufacturer??
Wait - I lied - I did need some 1/2" long 8-40 screws for something - got a few from someone here on CGN.
I do recall, at least once, needing two new #6-48 screws - was in a Cabela's (?) store and bought a weaver base that came with the screws I wanted. Was cheaper than ordering two screws.
