recently i got a 2.5x20mm Simmons shotgun scope i wanted to use on my 45LC carbine barrel....i mounted it with the factory scope base and it worked but wasn't happy with the ring spacing the way it worked out so i bought a weaver 82 and started comparing them and realized to get it how i wanted i'd need another slot in the base so i marked it where i wanted it and turned it upside down and did the groove on my table saw and it came out perfect...used the existing slot to set height of blade,then set up the rip fence so when the end of the base was against it the blade would cut the slot where i wanted it. Then i checked and adjusted the saw's push square(used another square to check it),fired up the saw,and held the base against the push square and the rip fence and pushed it thru once...perfect but not wide enough. Then i moved the rip fence 1/2 a blade width closer to the blade and pushed it thru again...almost.Moved the fence 1/2 blade closer to the blade,pushed it thru again and the slot width was perfect. Now i have the rings spaced as far apart as they can go on that scope,very happy with it. The slot i cut looks like it was done by a machinist.