Scope Bases

MOA stands for minute of angle, a unit of angle equal to 1/60 of a degree. At 100 yards, 1 MOA covers about 1.047 inches, roughly an inch. At 200 yards it is about 2 inches, at 500 yards about 5 inches. Scope turrets, reticles and canted bases are all measured in MOA (or in MRAD, the metric alternative).

A canted base tilts the scope slightly nose-down, so the scope starts with built-in elevation. A 20 MOA base adds about 21 inches of elevation at 100 yards, which lets your scope reach farther before it runs out of turret travel.

Most hunters and mid range shooters do well with a flat 0 MOA base. For long range, 15 to 30 MOA is the most common choice, with 20 MOA the standard. Extreme long range shooters sometimes run 40 or 50 MOA. Check your scope's total elevation travel and make sure you can still zero at 100 yards with the cant you choose.

Both measure angle. 1 MRAD equals about 3.44 MOA. Canted bases are usually listed in MOA, while many precision scopes use MRAD turrets. A 10 MRAD base adds about the same elevation as a 34 MOA base. You can mix a MOA base with a MRAD scope; the cant only shifts your starting point.

Only if you plan to shoot at long range and need more elevation than your scope offers on its own. For most hunting and mid range shooting, a flat base works well.

Usually, yes. Picatinny rings may not fit a Weaver base because Weaver slots can be narrower. Check your ring and base specs before mounting.

Match the make, model, action length and handedness of your rifle. Receivers and screw patterns vary, even within one brand, so confirm fitment on the product page.

Most rimfires use a dovetail instead. Look at our dovetail to Picatinny rails, including Pete's Pillars rails for the CZ 457.