SAAMI - Abbreviation for Sporting Arms and Ammunition Manufacturers’ Institute.

Safety Shooting Glasses - Eye protection and sight improvement specifically designed for, and which should always be used, when shooting firearms.

Scope - A shortened form of the word "telescope", meaning a telescopic sighting device for a firearm or, simply "riflescope". While a telescope magnifies an image, a riflescope is made with an integral fire-direction indicator called a reticle which, most often, appears as crossed-hairs or crossed-wires. A riflescope is securely mounted on a firearm and adjusted so that its vertical cross-wire is aligned with the path of the fired projectile. The horizontal cross wire is then set to coincide with the projectile's point of impact at a specific distance. It magnifies the target and places it and the reticle in the same optical place, facilitating very precise aiming.

Scope Mounts - Devices for securing a scope to a rifle, comprising scope rings and bases.

Scout - An individual who is usually ahead of his parent organization to conduct surveillance on the enemy, conduct reconnaissance, and report information to his parent organization.

Sear - That part of a trigger mechanism ( usually a notch or shoulder on the trigger arm ) which holds the striker ( hammer or firing pin ) in the cocked position until the trigger is pulled. Cocking the striker against its spring automatically engages the sear. Pulling the trigger disengages the sear, releasing the striker onto the primer.

Season Crack - A cracking which occurs in hard brass with the passage of time.  Usually seen in cartridges as Split necks.

Seating Depth - The depth to which a bullet is seated below the case mouth.

Seating Die - The reloading die that presses the bullet into the neck of the cartridge case, crimping the case if so desired.

Sectional Density ( SD ) - A mathematical factor expressing the ratio of a bullet’s mass ( weight ) to its cross sectional area. SD relates a bullet’s diameter to its length ( in a given calibre, the heavier a bullet is, the longer it is ). All other factors being equal, bullets that are longer in relation to their diameter retain their velocity better, hence have flatter trajectories, hit with higher energy, and penetrate deeper, than bullets that are shorted relative to their diameter. SD does not take into account the aerodynamic shape of a bullet, which also influences velocity retention, trajectory, etc. Useful only for comparing bullets of similar shape, or when incorporating into Ballistic Coefficient factors.

Semi-automatic / Semi-auto - Term to describe a firearm of firearm action that is self-loading. The action is cycled ( or “cocked” ) by hand to feed the first round into the chamber, thereafter it cycles, ( i.e. fires, extracts, ejects and reloads ) automatically each time the trigger is pulled, until the magazine is empty. Can be gas-operated or recoil-operated. Semi-autos will fire one shot only - pressure on the trigger must be relaxed and reapplied for each shot. Such weapons are often wrongly called automatics.

Semi-rimmed Case - See Rim

Service Rifle - The primary rifle of a military force.

Set Trigger - Trigger mechanism with two different weights of pull, one normal or heavy, and one very light ( aka a “hair trigger” ). There are two types: a single set trigger, the “hair” setting of which is engaged by pressing the trigger forward prior to firing ( otherwise it works as a standard trigger ); and a double set trigger, which comprises two separate triggers, the rear of which does not fire the piece, but is pulled to set the front one on "hair" ( failing which the front one will work as a standard trigger ).

Shank - The parallel-sided or cylindrical section of a bullet.

Shellholder - In a reloading press, the bracket fitted to the top of a ram, which grips the case rim to secure the case for sizing, decapping, bullet seating, etc.

Shells - In smallarms terms, slang for cartridges, especially shotgun cartridges ( USA: "shotshells" ). Rarely used to mean cartridge cases, except as in shellholder.

Shock - The transference of the kinetic energy of a bullet to animal tissue or other mediums.

Shoulder - The sharply tapering section of a bottleneck cartridge case which separates the neck from the case walls.  ( Click here for picture. )
Or, in bullet terms, the point at which the head of a projectile joins the cylindrical rear portion, or shank.

Side-by-side - In double-barrelled weapons, barrels horizontally aligned, one beside the other, as distinct from an over-under.

Side-plate - A removable plate in the frame or receiver to allow access to internal parts or upon which some internal parts are mounted.

Sight-in - In rifle shooting, the process of getting the bullet’s point of impact to coincide with the rifle’s point of aim ( or line of sight ) at a preselected distance, by means of sight adjustment. Applies to any given combination of rifle, load and sight system. See Line of Sight, Trajectory, Zero.

Sight Picture - The visual image observed by the shooter when the firearm sights are properly aligned on the point-of-aim.

Sight Radius - The distance between the front and rear elements of mechanical or “iron” sights. Theoretically, the longer the sight radius, the lower the potential for human optical error, hence the more accurate the system. This is true of open sights on longer barrelled rifles, which can have a long sight radius while still keeping the rear sight the proper distance from the shooter’s eye. If the rear sight is too close to the eye, it creates focus problems, potentially affecting aim ( unless it is an aperture or peep sight, which obviates the need for focusing ). For this reason bloop tubes are sometimes used on short-barrelled rifle to extend the sight radius.

Silencer - See suppressor .

Silhouette - A shooting sport characterised by metallic knockdown targets of various shapes and sizes, at various distances, invented in Mexico. Variations include rifle and handgun in centerfire, smallbore and air gun calibres.

Single Action - An action requiring the manual cocking of the hammer before sufficient pressure on the trigger releases the firing mechanism. (abbr. SA), as opposed to double action.

Single Base Powder - Smokeless propellant made from nitro-cellulose base. See Double base powder, Nitro-cellulose.

Single Shot Action - A firearm with no means in the mechanism for storing or loading more than the cartridge housed in the chamber of the barrel.

Single Stage Trigger - Trigger with no free movement prior to releasing the sear; as distinct from double stage ( aka double pull or military type ) which requires some additional “slack” to be taken up before it releases the sear.

Sizing - See Resizing

Six o’clock Hold - A sight picture in which the top of the front sight post or bead is held on the bottom edge of the bull’s-eye, as in the 6 o’clock position on a clock face. Firearm must be sighted in to shoot slightly high of point of aim at that distance, so that bullets land in the centre of bull’s-eye. Purpose is to enable the shooter to see the full circle of the bull’s-eye for more precise reference, rather than to partially obscure it with the foresight.

Slide - A member attached to and reciprocating with the breech block.

Slug - Verb ( as in “slug” the barrel ): the process of determining the precise groove diameter of a barrel by driving a slightly oversized soft lead lug through the bore and measuring its broadest diameter.
Noun: slang for bullet.

Smokeless Powder - Propellant based on nitro-cellulose, or nitro-cellulose and nitro-glycerine. Smokeless powder gives off no smoke and is non-corrosive, as distinct from black powder which creates voluminous clouds of white smoke and leaves corrosive deposits in the bore. Smokeless powder largely replaced black powder during the 1880s and 1890s; it facilitates higher velocities but generates higher pressures. See Nitro Proofing.

Sniper Specialist - An individual trained in sniper employment (preferably sniper qualified) who advises the commander or operations officer (S3) on proper sniper employment.

Sniper Team - Two snipers of equal training and ability; the foundation of sound sniper employment.

Soft Nose Bullet / Soft Point Bullet - A bullet design providing for exposure of a portion of the core at the nose or tip of a jacketed bullet to initiate expansion for the bullet to “mushroom” in the target.

Soft Head - Spreading of the head and opening of the primer pocket on firing, due to over-annealing of the head of the cartridge.

Solid Nose bullet / Solid - Traditionally, a jacketed bullet with “blind” nose, i.e. no lead exposed at the tip ( non-expanding ) designed for maximum penetration on large game. Also called Full Metal Jacket ( FMJ ) bullets. Term now also applies to bullets that are lathe-turned from copper, brass, etc., known as monolithic.

Speed of Sound - 1120.22 fps at standard conditions. Projectiles travelling faster than this pass through the sound barrier twice. Once as it exceeds the sound barrier (within the barrel) and once when it re-enters subsonic speeds. This effect causes a sonic crack that can be used to pinpoint the firer.

Spire Point - ( Bullet ) Pointed conical bullet. Same as Soft Point, also abbreviated SP.

Spitzer - A bullet design having a sharp pointed, long ogive.

Split Body - A longitudal crack in the body of the case near the head.  This is a dangerous defect, as it allows gas to escape to the rear.

Split Neck - A crack in the neck of the case.  It is usually due to failure to anneal the neck sufficiently to prevent Season cracking.

Stabilize - In rifles, to put the right amount of spin on a bullet ( by means of the spiral grooves in the bore ) to enable it to maintain an equilibrium in flight. A bullet that rotates on its own long axis at the correct rate will fly true; one which does not spin at all, or spins too slowly or too rapidly for its length, will wobble or tumble, causing it to be inaccurate and fall short. See Keyhole, Rate of Twist.

Stalking - The sniper's art of moving unseen into a firing position, engaging his target, and then withdrawing undetected.

Stock Dimensions -General stock dimensions consist of the following: cast, drop at comb/Monte Carlo/heel, girth, length of pull, length of stock, pitch.

Stock Weld - The contact of the cheek with the stock of the weapon.

Stovepipe - Malfunction occurring when a case gets stuck between the breech face and the slide.

Straight Pull - Type of bolt action operated by pulling straight back on the handle, instead of first rotating the bolt by hand ( the bolt self-rotates on a camming system ). Well-known examples are Ross ( Canadian ), the Schmidt-Rubin ( Swiss ) and the modern Blaser ( German ).

Stretch - A visible strain extending around the case above the head.  Usually due to excessive headspace.

Striker - In rifles, a spring-propelled firing pin, or internal hammer which strikes the back of the firing pin.

Suppressor - A device designed to muffle or eliminate the sounds of the discharging of a firearm. It is usually fitted onto the muzzle but can also be an integral assembly with the barrel. This usually works best with subsonic ammunition to eliminate the bullet's sonic crack as well.

Surveillance - The systematic observation of areas, places, persons, or things by visual, aural electronic, photographic, or other means. The sniper makes extensive use of fixed and roving surveillance to acquire targets or assess target vulnerabilities.

Swage -  To pressure-form by forcing through or into a die.  Normally used in reference to cast bullets.

Swivel - The attachment point for the sling to the stock.

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