Since the scope only provides a sighting reference any power is usable. 12X would certainly work. For competition many shooters use 16x and higher to better see the target center. The downside of high magnification is when the mirage is particularly heavy. It's like looking through a fish bowl. Probably more important would be a scope that has exceptional tracking and repeatability. Big target knobs with solid click stops would be another important feature. The reticle would be the choice of the shooter but the single dot is popular.
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