If by swing base, you mean the old Weaver pivot mount where the scope can be pivoted to one side to allow immediate use of iron sights, I think it's a good one. Back in 1963 dad got a Win 70 featherweight for me for hs graduation and I put a Leupold 4x in one of those mounts on the rifle. I still have it and it has always returned to zero, never a problem in 55 years. If they still made them I would put them on a couple of other rifles I have that have open sights, they are much handier than the quick detacheable type mounts.