Small Arms

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Ultimate Firearms Training Guide

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There are five general categories of small arms: handguns, rifles, shotguns, submachine guns, and machine guns.


There are four basic types of handguns:

1. Single-shot pistols

2. Derringers

3. Revolvers

4. Auto-loading pistols (automatics)

Single-shot pistols. A single-shot pistol has one firing chamber integral with the barrel, which must be loaded manually each time the weapon is to be fired (Figure 1.1A).

Derringers. They are a variant of single-shot pistols. Derringers are small pocket firearms having multiple barrels, each of which is loaded and fired separately. The traditional derringer has two barrels (Figure 1.1B).

Cylinder Pin For Pistol
Figure 1.1 (A) Single-shot pistol; (B) derringer.

Revolvers. The revolver is the most common type of handgun in the United States. Revolvers have a revolving cylinder that contains several chambers, each of which holds one cartridge. The cylinder is rotated mechanically so as to align each chamber successively with the barrel and firing pin. The first revolver was produced by Samuel Colt in 1835-1836.

There are three types of revolvers, the most common of which is the "swingout" (Figure 1.2A). On pressing the cylinder latch, normally found on the left side of the frame and pushing the cylinder to the left, the cylinder swings out, exposing the chambers. Each individual chamber is then loaded with a cartridge. The cylinder is then swung back into the frame, engaging the cylinder latch. The weapon is now ready to be fired. After discharge of all the cartridges, the cylinder latch is pressed and the cylinder is swung out.

An ejector rod, affixed to the front of the cylinder, is pressed to the rear, ejecting the fired cases. The cylinder is now ready to be reloaded.

In break-top revolvers, the frame is hinged at the rear such that, on release of a top catch, the barrel and cylinder swing down, exposing the back of the cylinder for loading (Figure 1.2B). The opening action will also eject empty cases from the cylinder. This form of weapon is relatively uncommon in the United States, but is the traditional form of revolver in Great Britain.

Swing Out Revolvers
Figure 1.2 (A) A 9-mm revolver, swing-out type, with cylinder swung open exposing chambers; (B) break-top revolver with action open.
Gunshot Wounds The Arm

Figure 1.3 Solid-frame revolver with loading gate swung open. Arrow points to loading port where individual cartridges are inserted.

The solid-frame revolver is the oldest form of revolver, dating back to Colt's original weapons (Figure 1.3). In this weapon, the cylinder is held in the frame by a central pin, around which it rotates. The back of this cylinder is never exposed completely by either "swinging out" or "breaking open." Each chamber in the cylinder is loaded individually through a loading gate on the right side of the frame. The hammer of the weapon is typically pulled back to half cock, and the cylinder is then manually rotated so that a chamber is aligned with the loading gate. A cartridge is inserted. The cylinder is then manually rotated to the next chamber and a second cartridge is inserted. This procedure is continued until the cylinder is completely filled. After the weapon is discharged, the cylinder has to be manually rotated again and aligned with the loading gate, and each cartridge is ejected through the gate using the ejector rod. This type of construction is most commonly encountered in single-action revolvers and the early model Saturday Night Specials. The latter term, dating back to the turn of the century, refers to a cheap weapon usually of poor construction and does not refer to concealability.

Revolvers may be either single-action or double-action types. In single-action revolvers, the hammer must be cocked manually each time the weapon is to be fired. Cocking the hammer revolves the cylinder, aligning the chamber with the barrel and the firing pin. Pressure applied to the trigger then releases the hammer, discharging the weapon. In double-action revolvers a continuous pressure on the trigger revolves the cylinder, aligns the chamber with the barrel, and cocks and then releases the hammer, firing the weapon. Most double-action revolvers may be fired in a single-action mode. The amount of pressure on a trigger necessary to fire a well-made double-action revolver varies from 12 to 15 lb. If these weapons are cocked and fired in single-action mode, less pressure (2-4 lb) is necessary to fire them. The double-action trigger pull for cheap, poorly made revolvers is usually much greater, while single-action trigger pull may vary from less than a pound to as much as the double-action pull in a well-made revolver.

Many single-action revolvers have a "half-cock" notch in the cocking hammer that lies between the position of "full cock" and "fired." The purpose of the half-cock notch is to catch the hammer if it accidentally slips from the thumb as it is being manually cocked. Many individuals incorrectly consider the half-cock notch a safety position and will carry weapons on "half cock." Dropping a weapon when on half cock may cause the hammer to disengage, fly forward, and discharge the weapon. Some single-action revolvers will fire from the half-cock position if the trigger is pulled. Ruger single-action revolvers equipped with a safety bar do not have a half-cock notch.

The cylinder of a revolver may rotate either clockwise (Colt revolvers) or counterclockwise (Smith & Wesson revolvers). This difference has resulted in a number of deaths among individuals playing Russian roulette, in which an individual loads one chamber of a revolver and spins the cylinder. They then "peek" to locate the cartridge. If it is in any cylinder except the one that will be rotated into firing position on pulling the trigger, the gun is then put to the head and the trigger pulled. If the cartridge is in the lethal chamber, the player makes some excuse to spin the cylinder again. This system of playing Russian roulette is theoretically "safe" if one knows which way the cylinder rotates. A person familiar with playing the game using a Colt revolver may try it with a Smith & Wesson revolver in which the cylinder rotates in the opposite direction and may experience a fatal conclusion to the "game."

Auto-loading pistols (automatics). Auto-loading or automatic pistols make up the fourth category of handguns. The term "automatic pistol" is a misnomer, as this form of pistol is an auto-loader in which the trigger must be pulled for every shot fired. Regardless of the correct terminology, however, these weapons are invariably called "automatics" or just "pistols." These pistols use the forces generated by the fired cartridge to operate the mechanism that extracts and ejects the empty cases, loads the fresh cartridge, and returns the mechanism into position to fire the next round (Figure 1.4). The first commercial automatic pistol was produced in 1893 by Borchardt; this weapon was the predecessor of the Luger.

The cartridges are almost invariably stored in a removable magazine in the grip of the pistol. Some automatic pistols, such as the Intratec Tec 9, and the Mauser M1896, have the magazine in front of the trigger guard. The Calico Auto Pistol uses a 50 or 100 round helical-feed magazine on the top

Tec Front Grip
Figure 1.4 (A) The weapon has just been fired. The slide has begun to recoil with the bullet a few inches in front of the muzzle. (B) The slide has recoiled all the way back. The fired cartridge case is being ejected and the gun cocked. The slide will now come forward, chambering a new round.

rear of the frame. The term "clip" is often used synonymously with the term "magazine." In fact, a clip is a device designed to facilitate the loading of a number of cartridges into a magazine, however, most people use the terms interchangeably.

There are five methods of operation of automatic pistols: blow-back, delayed or retarded blow-back, blow-forward, recoil, and gas. Only two of these methods are currently in widespread use: blow-back and recoil. In a blow-back action, the pressure of the gas produced by combustion of the powder forces an unlocked slide to the rear, thus starting the cycle of extraction, ejection, and reloading.

Heckler and Koch P7 pistols are blow-back-operated pistols with a recoil breaking system that delays breech opening (Figure 1.5). On firing the gun, part of the propellant gas is directed through a small vent in the barrel ahead of the chamber into a cylinder beneath the barrel. A piston attached to the slide enters the front end of this cylinder. The gas entering the cylinder acts against the piston, such that as the slide begins to move rearward by virtue of the recoil pressure, the movement of the piston in the cylinder is resisted by the gas pressure, delaying the movement of the slide and delaying the opening of the breech. Another unusual feature of this weapon is that the firing pin is cocked by a squeeze cocker incorporated in the front of the grip (Figure 1.5). On grasping the grip, the fingers depress the squeeze cocker, automatically cocking the gun. If the pressure on the grip is released, the squeeze cocker goes forward uncocking the gun. P7 pistols have fluted firing chambers and polygonal rifling of the barrels (see Chapter 2).

In a recoil-operated automatic pistol, the barrel and the slide are locked together at the moment of firing. As the bullet leaves the barrel, the rearward thrust of the propellant gas on the cartridge case starts the barrel and slide moving to the rear. After a short distance, the barrel is halted, and the locking device is withdrawn from the slide (Figure 1.6). The slide then continues to the rear, ejecting the fired case and starting the reloading cycle.

Traditionally, automatic pistols have had at least one manually operated safety device. Manual safeties are thumb pieces or buttons that are mounted on either the slide or receiver (Figure 1.7). Customarily, on the left side, they are now often ambidextrous or reversible. Putting on the safety locks the firing mechanism (hammer, striker, and sometimes sear) and prevents the weapon from discharging. Less commonly, automatic pistols, e.g., the Colt M1911, are equipped with grip safeties (Figure 1.7), movable pieces mounted in the grip which prevent connection between the trigger and the sear except when the pistol is held firmly in the hand, ready for shooting. The grip safety is held out by springs when at rest. Grasping the grip pushes the piece in and permits connection between the trigger and sear and thus firing of the weapon.

Many of the newer double-action automatic pistols have a thumb piece on either the slide or frame which externally resembles the usual safety lever but is in fact a decocking lever (Figure 1.8A). It may be on the left side, ambidextrous or reversible. When this thumb piece is pushed down, the hammer falls. The weapon will not discharge, however, as the thumb piece locks the firing pin and/or rotates a steel surface between the hammer and the firing pin to prevent contact between the two. In some weapons, the decocking lever now functions as a safety and the weapon will not fire as long as this device is down. Other automatic pistols do not have any manual safety but only a decocking lever, e.g., Sig-Sauer (Figure 1.8B). In such guns, depressing the thumb piece causes the hammer to drop, putting the gun on

Gunshot Wound

Figure 1.5 (A) Heckler-Koch P7 9-mm pistol with squeeze cocker constituting front portion of grip; (B) Disassembled with piston visible and projecting downward from end of slide.

Figure 1.5 (A) Heckler-Koch P7 9-mm pistol with squeeze cocker constituting front portion of grip; (B) Disassembled with piston visible and projecting downward from end of slide.

a double action mode but not putting on a safety. The Glock pistols have neither a manually operated safety nor a decocking lever.

The Sig-Sauers, as well as most of the newer quality automatics, are equipped with a firing pin safety (lock). This internal device locks the firing pin in place preventing forward movement and thus accidental discharge. In order to fire the weapon, the trigger must be pulled back in order to disengage this safety.

Homemade Pistol

Figure 1.6 Locking action of recoil-operated locked breech automatic pistol. On firing, the slide (A) and barrel (B), which are locked together by the ribs (C), recoil. After a short distance, the barrel is haltered by a bar (D) engaging the barrel lug (E). The ribs disengage and the slide continues backward to extract and eject the fired cartridge case. The slide then comes forward to chamber a new round and cock the weapon.

Figure 1.6 Locking action of recoil-operated locked breech automatic pistol. On firing, the slide (A) and barrel (B), which are locked together by the ribs (C), recoil. After a short distance, the barrel is haltered by a bar (D) engaging the barrel lug (E). The ribs disengage and the slide continues backward to extract and eject the fired cartridge case. The slide then comes forward to chamber a new round and cock the weapon.

Gunshot Pics Sides
Figure 1.7 Left side of Colt .45 automatic pistol with manual safety and grip safety (arrow).
Gunshot Wounds From Auto Hollowpoint
Figure 1.8 (A) Beretta with decocking lever/safety mounted on slide (B) Sig Sauer P226 with decocking lever (but no safety) on frame above magazine button.

Some pistols have a device that tells whether the chamber contains a cartridge. This may be a protruding pin at the rear of the slide or just protrusion of the extractor. Some automatic pistols have magazine safeties. This device prevents discharge of the weapon when the magazine has been removed from it. In some weapons, it is possible to deactivate or remove this device.

With rare exceptions, currently manufactured revolvers do not have manually operated safety devices. This fact seems to have escaped British writers, who in their detective and action fiction always have their characters putting on and taking off the "safety" of their revolver. Although thumb safeties are not present on modern revolvers, Smith & Wesson did at one time manufacture a model with a grip safety. As regards derringers, they may or may not be equipped with a push-button safety that blocks the fall of the hammer.

Preparing an automatic pistol to fire involves two steps. First, the loaded magazine is inserted into the grip. The slide is grasped, pulled rearward, and released. A spring drives the slide forward, stripping a cartridge from the magazine and loading it into the firing chamber. The weapon is now cocked and ready to be fired. If the weapon has a manually operated safety, the safety may now be applied and the weapon carried in a cocked-and-locked mode. Alternatively, the weapon may be decocked using the decocking switch or by holding the hammer back (usually with the thumb), pressing the trigger and gradually lowering the hammer. In the case of weapons of older design (the Colt M1911, the Browning HiPower), to fire the gun after the hammer is lowered, the hammer must be manually recocked for the first shot. After the first shot, the operating mechanism of the automatic pistol automatically cocks the hammer. Most auto-loading pistols are now equipped with a double-action trigger that will cock and fire the first shot as a result of continuous pressure on the trigger. In these weapons, after the hammer is lowered, in order to fire, one just pulls the trigger. After this, the weapon automatically cocks itself for each succeeding shot. Even in double-action automatic pistols, however, the slide must be pulled back initially to chamber a cartridge.

Some of the newer double-action auto-loading pistols are manufactured in a number of variations. Thus, they can be purchased double action only and with or without safety levers. Browning has a model, the BDM (Browning Double Mode), that has a screw-slotted selector on the left side of the slide. Using it, the trigger and hammer can be set for conventional double/single action or double action only.

The Colt Model 2000 (now discontinued) had a sliding trigger; turningbarrel locking system; polymer frame; slide latch; hammerless striker and automatic internal striker block that is cleared only in the last fraction of trigger movement. It only fires in the double-action mode.

Beretta manufactures auto-loading pistols with a tip-up barrel for first-round loading (Figure 1.9). In this weapon, a loaded magazine is placed in the grip. A latch is depressed on the side of the frame and the barrel tips up exposing the firing chamber. A cartridge can then be inserted directly into the firing chamber. The action is then closed and the weapon is now ready to fire. A round can also be chambered the traditional way by pulling back and releasing the slide.

Following its introduction into the United States, the Glock pistol became involved in controversy when members of the media and some politicians contended it was a "plastic gun" that was not detectible by x-ray or metal detectors. This is, of course, nonsense. While the gun does have a polymer

Pistol With Tips Barrel
Figure 1.9 Beretta with tip-up barrel.

frame, the slide, barrel, and internal components are steel. Since then, a number of other pistols with polymer frames have been introduced.


A rifle is a firearm with a rifled barrel which is designed to be fired from the shoulder. Barrel length is immaterial in classifying a firearm as a rifle. However, U.S. Federal law requires rifles to have a minimum barrel length of 16 inches. The types of rifles commonly encountered are single-shot, lever-action, bolt-action, pump-action, and auto-loading. A single-shot rifle has one firing chamber integral with the barrel which has to be manually loaded each time the weapon is fired. A lever-action rifle has a lever beneath the grip which is used to open the rifle action, to extract the cartridge case, and, in closing the action, to insert a fresh cartridge in the firing chamber and to cock the gun.

In a bolt-action rifle, a handle projects from a bolt. Pulling back and pushing forward on this projection causes the bolt to extract and eject a cartridge case and then to insert a new cartridge while cocking the gun. The slide-action rifle uses the manual movement of a slide under and parallel to the barrel to open the action, extract and eject a cartridge, load a fresh cartridge, and cock the weapon.

In auto-loading or semi-automatic rifles, the weapon fires, extracts, ejects, reloads, and cocks with each pull of the trigger using the force of gas pressure or recoil to operate the action. After each shot the trigger must be released and then pulled again to repeat the cycle. Auto-loading rifles are commonly but incorrectly called "automatic rifles." A fully automatic rifle is one that, on pulling the trigger and firing the weapon, utilizes the force of gas pressure or recoil to eject the fired case, load the next round, fire it, and then eject it. This cycle is repeated until all the ammunition is used or the trigger is released. Automatic weapons are generally used only by military and police organizations. While it is possible to alter some semi-automatic rifles to deliver automatic fire, unlike the impression given by the media and some politicians, this is not a simple procedure. In fact, such conversions are uncommon. In the United States, deaths due to full-automatic weapons (rifles and submachine guns) are extremely rare. The author has seen only three such deaths in the past 30 years, all of which occurred in the same incident and involved illegal drug dealings and an alleged professional killer. Weapons ffired in the full-automatic mode are very difficult to control. In most instances, while the first shot may be on target, subsequent rounds fly high and to the right.

Assault Rifles

The term "assault rifle" refers to a rifle that is: (1) auto-loading, (2) has a large-capacity (20 rounds or more) detachable magazine, (3) is capable of full-automatic fire, and (4) fires an intermediate rifle cartridge. This term has been corrupted by the media and some politicians to include most self-loading weapons. They have also coined the meaningless term "assault pistol" which appears to refer to large, ugly-looking pistols having large-capacity magazines (20 to 40 rounds) or to semi-automatic versions of submachine guns such as the Uzi (Figure 1.10). "Assault pistols" are with rare exception cumbersome, difficult to shoot, inaccurate, and cheaply made. They are usually acquired by individuals with little knowledge of firearms who associate the effectiveness of a weapon with "ugliness."

Weapons that fire pistol ammunition are not by definition assault rifles, nor are self-loading rifles with fixed magazines that were never intended for full-automatic fire. The best example of the latter weapon is the SKS-45 (Figure 1.11). While this weapon is an auto-loader and chambered for an intermediate-power cartridge, it has a fixed ten-round magazine and was never intended for full-automatic fire. The weapon may be altered to accept a 30-round magazine, however.

There is a group of weapons that might be considered "assault rifles" if one eliminates the criteria of full-automatic capability. This would include weapons such as the AKS-47, MAK-90 and Colt AR-15 Sporter and their variants (Figure 1.12). These are semi-automatic versions of the AK-47 and M-16 assault rifles.

Maadi Griffin For Sale
Figure 1.10 Intratec Tec 9 often referred to as an "assault pistol," is just a cumbersome, ugly-looking pistol with a large magazine capacity.

One of the common fallacies about assault rifles is that the wounds they produce are more severe than those due to ordinary centerfire rifles. In fact, the wounds are less severe than those produced by virtually all hunting rifles even the Winchester M-94 (introduced in 1894) and its cartridge the .30-30 (introduced in 1895). As we shall see in Chapters 3 and 7, in dealing with rifles, the severity of the wound is determined by the amount of kinetic energy lost by a bullet in the body. The intermediate cartridges used in assault rifles possess significantly less kinetic energy than a regular centerfire rifle cartridge

Assault Rifle Wonds

Figure 1.11 SKS-45.

Wounds From Assault Rifles
Figure 1.12 Chinese AKS-47 semi-automatic rifle.

designed for hunting. In addition, since most ammunition used in these weapons is loaded with a full-metal jacketed bullet, the wound is even less severe than one might expect.


A shotgun is a weapon that is intended to be fired from the shoulder; it has a smooth bore and is designed to fire multiple pellets from the barrel. Again, barrel length is immaterial in classifying a firearm as a shotgun, although U.S. federal law requires a minimal barrel length of 18 inches. A shotgun may be classified as a single-shot, over-and-under, double-barrel, bolt-action, lever-action, pump-action, or auto-loading. The over-and under shotgun has two barrels one above the other, and the double-barrel version has its barrels side by side. The two barrels in these weapons are often of different choke.

Submachine Guns/Machine Pistols

A submachine gun or machine pistol is a weapon that is designed to be fired from either the shoulder and/or the hip; is capable of full-automatic fire; has a rifled barrel, and fires pistol ammunition. It is often incorrectly called a "machine gun." Semi-automatic carbines (excluding the M-1 Carbine) are a variation of submachine guns. These are either semi-automatic versions of submachine guns or weapons that have the external appearance of a submachine gun. The media has dubbed these "assault pistols." In the case of semiautomatic versions of submachine guns, the internal mechanism is typically so altered that they are essentially a different weapon.

Machine Guns

A machine gun is a weapon that is capable of full-automatic firing and that fires rifle ammunition. It is generally crew-operated, but some forms may be fired by single individuals. Most machine guns have the ammunition fed by belts, although some use magazines.

Caliber Nomenclature for Rifled Weapons

Rifles, handguns, submachine guns, and machine guns have rifled barrels; that is, spiral grooves have been cut the length of the interior or bore of the barrel (Figure 1.13). Rifling consists of these grooves and the metal left between the grooves — the lands.



Figure 1.13 Cross-section of barrel showing lands and grooves.

In the United States, the caliber of a rifle or handgun is supposed to be the diameter of the bore, measured from land to land. This measurement represents the diameter of the barrel before the rifling grooves were cut. In reality, however, caliber may be given in terms of bullet, land, or groove diameter. Caliber specifications using the U.S. system are neither accurate nor consistent, i.e., the .303 Savage fires a 0.308-in.-diameter bullet, while the .303 British cartridge has a 0.312-in.-diameter bullet. Both the .30-06 and the .308 Winchester cartridges are loaded with bullets having a diameter of 0.308 in. The "06" in .30-06 refers to the year of adoption of this cartridge. American cartridges that originally used black powder are designated by caliber, the original black powder charge, and, in some cases, bullet weight. Thus, the .45-70-405 cartridge has a 405-gr. bullet, 0.45 in. in diameter, and was originally propelled by 70 grains of black powder. The term "grains" refers to the weight of powder, not the number of granules of powder. A few of the smokeless powder cartridges that came out in the late-nineteenth century also used this method of designation. Thus, the .30-30 cartridge has a 0.308-in.-diameter bullet originally propelled by 30 gr. of smokeless powder.


Cal Gunshot Wounds Pictures

Figure 1.13 Cross-section of barrel showing lands and grooves.

With the development of newer types of powder, this powder charge is no longer used.

The best example of confusing caliber designation and the one most significant to the forensic pathologist involves the .38 Special and .357 Magnum cartridges. Weapons chambered for these calibers have barrels with the same bore and groove diameters. Bullets loaded in each of these cartridges have identical dimensions. The .357 Magnum revolver chambers and fires all .38 Special ammunition, although a weapon chambered for a .38 Special cartridge cannot ordinarily chamber and should never use the .357 Magnum cartridge. The .357 Magnum cartridge case is, in fact, the .38 Special cartridge case lengthened and loaded with additional propellant. Except for the difference in the length of the cartridge cases, all other physical dimensions are the same for both calibers.

The European system of cartridge designation, which uses the metric system, is more thorough and logical than the U.S. system. It clearly and specifically identifies a cartridge by giving the bullet diameter and the case length in millimeters, as well as by designating the type of cartridge case. Thus, the Russian rimmed-service round becomes the 7.62 x 54 mm R. The 7.62 refers to the diameter of the bullet; 54 mm indicates the length of the cartridge case; and R indicates that the round is rimmed. The letters SR are used for semi-rimmed cases, RB for rebated cartridge cases, and B for belted cases. No letter is used to describe rimless cartridge cases. Thus, the .30-06 in the metric designation is the 7.62 x 63 mm.

The term "Magnum," is used to describe a cartridge that is larger and produces higher velocity than standard cartridges. In the case of shotgun ammunition, it may or may not be larger but does contain more shot than the standard shell.

A Wildcat cartridge is a nonstandard cartridge produced by a small company, independent gunsmith, or other individual; it is not available from major ammunition manufacturers.

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  • Espedito
    What system use to pull back barrel for shotgun?
    3 years ago

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