Best Picatinny Scope Bases

It describes how many minutes of angle the base tilts the scope downward at the front, relative to the bore. A 20 MOA base is not adding elevation adjustment directly; it is shifting where the scope's own erector sits within its existing range, converting unused down travel into usable up travel for shooting at distance.

Only if you intend to dial come-ups past roughly 500 to 600 yards. A canted base converts unused down travel into up travel, which is how a scope reaches distance. On a rifle shot inside 300 yards it does the opposite of helping, and can make the rifle impossible to zero because the erector runs out of down adjustment first.

Close, but not identical. A Weaver-pattern ring generally fits a Picatinny rail because Picatinny slots are more consistently spaced and slightly wider, but a Picatinny-pattern ring does not reliably fit a Weaver base, where slot spacing can vary between makers. Check the specific ring and base combination rather than assuming either direction works.

A one-piece base removes one alignment question, since there is no chance of the front and rear halves being torqued a fraction out of line with each other. A two-piece base is usually cheaper and has wider compatibility. On a bolt action shot inside a few hundred yards, either works fine once properly torqued and squared.

Whatever figure the base manufacturer publishes for your specific receiver, since it varies by base material and screw size rather than following one universal number. Base screws commonly run higher than ring screws, and an adjustable torque wrench covering both ranges is worth owning rather than guessing by feel.

Yes, and it is a common combination on precision builds. The base sets the overall cant relative to the bore, and lapped rings then remove any remaining bore misalignment between the two ring positions on top of that base. The two solve different problems and are frequently used together on the same rifle.