General stock dimensions consist of the following: length of pull, drop at comb, drop at Monte Carlo, drop at heel, pitch and cast.
A. Rifles 1. Cast is the lateral displacement of the centerline of the buttplate (pad) from the centerline of the bore. For a right-handed shooter, when the centerline of the buttplate is to the left of the bore, it is expressed as cast-on and to the right as cast-off. The opposite is true for left-handed shooters. 2. Drop is the vertical distance from the line of sight to the comb, Monte Carlo or heel of the stock. It is measured from an extension of a straight line drawn from the top of the front sight through the top surface of the open rear sight adjacent to the notch. The drops for target rifles are usually measured from the centerline of the bore. 3. Girth – The smallest circumferential dimension at the pistol grip. 4. Length of Pull – The distance from the center of the trigger to the center of the buttplate or recoil pad. 5. Length of Stock – The greatest dimension of the stock material. 6. Pitch – Not usually given for rifle.
B. Shotguns 1. Cast – Same as A.1., above. 2. Drop is the vertical distance from the line of sight to the comb, Monte Carlo or heel of the stock. It is measured from an extension of a straight line drawn from the base of the front bead sight across the highest point on the frame or receiver. 3. Girth – Same as A.3., above. 4. Length of Pull – same as A.4., above. 5. Length of Stock – Same as A.5., above. 6. Pitch is an expression used to indicate the relationship of the bore to the plane of the buttplate (pad). It is found by extending a line across the butt and drawing at right angles to this line an additional line through the highest point on the receiver or frame and measuring the distance from an extension of this line to a point at the base of the front sight bead. The pitch is said to be if the described line is above the front sight and if below. The pitch is normally down.