Scope rings that are machined will vary in height from the bottom of the ring to the bottom of the opening for the scope tube. Not naming names, but with one company’s rings, there can be over .010″ difference in actual ring height in the package!When you clamp your $3-400 scope down in such mounts, you are bending the scope tube! No way to treat your investment. On the other hand, rings that are extruded aluminum will be very consistent in height.If you use machined rings, I strongly recommend that you line-ream your rings. The old lapping method is ok, but tedious. If no one in your circle has such a reamer, as sold by Clymer/Brownell’s, etc., consider getting one yourself or seeing if your local ‘smitty has one. Or, maybe you can talk him into getting one on the condition that you and your buddies will give him business reaming all your scope rings.
After reaming a little out of the rings, you will be amazed by how much misalignment there is as evidenced by the amount of bluing or original finish that remains after the reamer has cut the high spots out.
Ream the rings after installing them on the base and with the top halves on, but the screws backed off. Tighten the screws a little to put tension on the reamer, but don’t overdo it. Remember, those 6×48 screws holding the base on (on most guns) aren’t all that strong, and on Contenders you only have about 4 threads holding each screw. If you start putting the “Armstrong” to it, you can strip or break screws and decidedly ruin your day. In fact, it may make you want to go to the door and slam the door on your fingers, simply because that would hurt less.
And yes, this is best done with the base installed on the barrel. Barrel diameters vary, and most will have some taper in the area where the base is installed. When you tighten the base down, it does bend slightly and will cause some misalignment of the rings.
Reaming corrects this.Further protect the scope by sticking an adhesive label in both the bottom halves and top halves. Paper performs miracles holding things in steel that want to slip, plus it protects the finish on your scope. I stick a generous size label in place, give the pocket knife a few strokes with the diamond EZ Lap, then neatly trim the labels to the edge of the ring openings.
All this other stuff I have seen is just stuff……..electrical tape, Loc-Tite, silicone, …… no need. Just paper is great. Adhesive labels just make it easier.