Calculating scope to rifle body clearance

The way you calculate the clearance is by halving the overall OUTSIDE diameter of your rifle scopes objective lens and then deducting half the rifle scopes body tube diameter.

For scopes with a 1" diameter body tube diameter this would mean deducting 12.7mm and 15mm for scopes with a 30mm diameter body tube.

Note we say OUTSIDE diameter - this means NOT the lens diameter, you need to measure the whole outer casing diameter.

The result gives you the minimum "saddle" dimension required - the measure from base of mount to bottom of the ring.

The amount the saddle dimension is greater than the figure you have calculated is the amount of clearance your scopes objective will be clear of your rifles body.  The saddle on these mounts is 13.6mm

Example -

1. A 44mm objective lens scope is measured and found to have an outer case measurement of 51mm.
2. 51 divided by 2 = 25.5.
3. 1" scope so deduct 12.7mm = 12.8mm
4. So the mount must have a saddle measure (base of mount to bottom of the ring) greater than 12.8mm or else it will ground out on the rifle body.

Calculating your rifle scopes clearance in this way does assume your dovetail or base is not raised above or below your rifles barrel. Note some rifles with high or adjustable cheek pieces may require higher scope mounts or risers so that your eye is in line with the rifle scope and your head is kept in an upright comfortable position.