STRAIN GAUGE

An electronic device to measure stress and strain in mechanical devices.

SWIVEL BOW

That part of a swivel which is in the form of an elongated loop and to which a sling or carrying strap is passed through or otherwise attached.

STEM (STEMMING)

A failure of a cartridge to feed in which the bullet jams against the top or bottom of the chamber. Also called Cock-Up or Cock-Down.

STIPPLING

The roughing of wood or metal with a pointed tool. It is normally performed to provide a gripping or decorative surface. Also called Matting.

STIRRUP

A component with divided legs to apply force equally. Mainly used in a trigger assembly where it is necessary to straddle another component.

STOCK

The wood or plastic component to which the metal parts of a firearm are attached to enable the shooter to hold the firearm.

STOCK BOLT

A bolt which passes through a buttstock lengthwise to secure it to the receiver or frame.

STOCK DIMENSIONS

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.

STOCK PITCH

The angle at which the buttplate or recoil pad slopes in relation to the bore axis. For method of measuring, see Stock Dimensions.

STOCK SCREW

A screw used for attaching the stock to the receiver or frame of a firearm. More than one may be used per firearm.