Variable Power
Variable power scopes give you a range of magnification settings. The most common variable-power scope on the market is the 3-9x 40 mm, and is probably the best choice for your Mini-14. This scope gives you a magnification range of three to nine times your normal vision and has an objective lens of 40mm. The objective lens allows light into your scope; a diameter of 40mm is more than adequate to give you a clear sight picture.
Fixed Power
Fixed power scopes are set at one specific magnification. If you decide to opt for a fixed power scope, choose one that will give you the best performance for the range of the Mini-14. A 4x40 mm power scope is generally considered a good magnification setting for this rifle.
Types of Crosshair Patterns
Scopes come with a variety of crosshair patterns. Traditional crosshairs feature two lines crisscrossing your sight picture vertically and horizontally. The intersection of these two lines represents the projected point of impact of your bullet. Tactical crosshairs feature mil-dots, or ranging marks, along the crosshairs, which give you the option of using your scope for determining range. Deciding on the type of crosshair pattern for your Mini-14 is a matter of personal preference.
Red Dot
A red dot scope is a good choice for your rifle, particularly if you will be engaging targets at short range. Red dot scopes do not magnify, but feature a red LCD light that is only visible through the scope. The visual effect is similar to using a laser beam, but without projecting a beam. These scopes work well for quickly acquiring targets without having to adjust your vision for magnification.