Principles of Small Arms Trivia Quiz

Answer: Any weapon with a calibre less than 20mm

The North Atlantic Treaty Organization classifies "small arms" as any weapon having a calibre less than 20mm. Some countries within NATO say less then 25mm.

Answer: Open Breech

Many modern machine guns fire from an open-breech position. Having the breech bolt lock open upon releasing the trigger virtually eliminates "cook-offs", or a cartridge self igniting because of high chamber temperatures transferring excessive heat through to the propellant.

Answer: Sear

A sear has a tail on it which sits in a bent (or notch) on the hammer. The trigger either directly or indirectly contacts the sear, which pivots it on its axis pin and disengages from the hammer, allowing it to slam forward and strike the firing pin.

Answer: Extractor Cam

The extractor rides up the sloped face of the extractor cam on forward movement so that it can be positioned behind the next round to be chambered. As the bolt moves rearward, the fired round is extracted from the chamber and the next live round is extracted from the belt at the same time.

The base of the cartridge sits in a "T" slot on the front face of the bolt which guides it into the chamber on forward movement.

Answer: Return Spring

A large spring is usually mounted on a guide shaft that the bolt rides on during rearward and forward movement. This spring is known as a return spring, and it not only slows rearward travel of the bolt, but also helps drive the bolt forward to chamber the next round.

A buffer assembly usually absorbs remaining recoil energy at the end of rearward travel to reduce metal-on-metal contact and premature part wear.

Answer: Chrome Plating

Chambers on modern firearms, as well as many older ones, are chrome plated to assist with primary extraction. During firing, the soft brass of the cartridge case expands and obturates with the chamber (eliminating rearward gas seepage). This heat and pressure makes the cartridge case difficult to extract.

The chrome plating allows the case to slip out of the chamber without rupturing or tearing the case.

Answer: Canadian barrels are hammer forged

Canadian C-7 barrels are hammer forged by their manufacturer, while American M-16 barrels are cut with a mandrel. This makes the Canadian barrels much more durable, and resistant to prolonged or sustained fire. It also makes our barrels more accurate, because our barrels are not succepted to extreme heat generated during the mandrel cutting process.

Answer: Blowback

In a blowback mechanism, the mass of the bolt and force of the recoil spring act to keep the breech closed as the cartridge is fired. Expanding gases from the fired round overcome this inertia and "blow back" the breech. The cartridge case keeps the chamber obtured until the bullet has left the barrel, and operating gas pressure and temperature has dropped to a safe level.

The remaining energy drives the bolt rearward to accomplish the unlocking, extraction, ejection and cocking cycles of operation.

Answer: 7

Rearward Movement: Unlocking, Extraction, Ejection, Cocking

Forward Movement: Feeding / Chambering, Locking, Firing

Answer: Integral to the design of the weapon

A mechanical safety is one that is built into, or integral to the design of a firearm. The weapon cannot funtion unless the mechanical safeties are disengaged. A good example is the magazine safety on a Browning Hi-Power. Unless a magazine is inserted, the tripping lever plunger will not be depressed. Thus, the tripping lever will not rise into position under the sear connecting arm, and the sear cannot be pivoted out of position to fire the weapon.

Answer: Clearance between the bolt face and chamber

Headspacing is a critical measurement taken to ensure that the cartridge case seats fully in the chamber. It is the clearance between the forward face of the bolt and the rear face of the chamber.

Answer: Breech explosion

If the weapon has excessive headspacing, it is possible to fire, but is extremely dangerous. If headspace is excessive, the cartridge will not fully seat in the chamber. This will allow a portion of the cartridge case to protrude from the chamber, allowing it to expand when fired. Brass is much softer than steel, and as a result, the energy that would normally push a projectile out the barrel and downrange will insted be vented out of a ruptured cartridge case inside your breech.

This will cause catastrophic failure of the breech, and will most likely blow up in your face.

A trained gunsmith has gauges to determine the permissible extent of headspacing.

Answer: Primer perforation

If the firing pin protrudes too much, it will perforate the primer. Perforation means simply that the firing pin will punch through the primer instead of percussing it. Cratering is caused by insufficient firing pin protrusion.

Answer: Chamber obturation

When the cartridge is fired, the soft brass of the case expands against the walls of the chamber, preventing the gas from venting to the rear. Thus, the full energy of the burning propellant pushes the projectile down the barrel. Obturation is a scientific term for sealing.

Answer: No

A supressor uses a series of baffles to slow the bullet to a sub-sonic speed before it leaves the barrel - this eliminates the ballistic "crack" heard by the supersonic projectile breaking the sound barrier. A silencer simply quiets the sound of the firing cartridge by providing a larger expansion chamber for the hot gas to go instead of inside the small barrel. People who incorporate the two terms to be the same do not know what they are talking about.