A quick walk through a well-stocked gun shop with today’s semi-automatic pistols might seem daunting – especially when it comes to understanding how semi-automatic pistols work. However, a mental dash through firearms history will help sort things out.

[in_content post=”104878″ alignment=”align-left” /]

Let’s go back to the 1100s, when the first man-portable “firearms” were invented. After the Chinese discovered gunpowder, it didn’t take long for them to determine that stuffing some of it in a bamboo tube, topping it with rocks, and igniting it would throw the projectiles farther and faster than human power could accomplish. Fast-forward to the mid-19th century, when mankind had refined firearms. But they were still essentially stuffing rocks down tubes on top of a charge of black powder and igniting it.

19th Century

Not satisfied with the six shots offered by most revolvers, Hugo Borchardt patented his C93 self-loading pistol with some help from his assistant Georg Luger. However, Borchardt’s ego got in the way of making changes to his design—the first mass-produced, magazine-fed, self-loading pistol—so the German military asked Luger to make some changes. He obliged, and by 1908, the iconic P-08 Luger, firing the 9x19mm Luger cartridge, was born.

America’s most prolific firearms inventor, John Moses Browning, patented his first firearm design in 1885. His discovery of the waste of burning powder gases led to his self-loading automatic machine gun designs. This quickly developed into semi-automatic pistol designs by 1899. His designs continued to improve, but his initial design—which incorporated a barrel surrounded by a shroud, creating the first pistol “slide”—is still the primary one used in most recoil-operated semi-automatic pistol designs today. Browning also produced some of the most popular pistol cartridges still in use, including the .25 ACP, .32 ACP, .380 ACP, and .45 ACP.

How Semi-Automatic Pistols Work

Understanding how pistols work will give you a deeper knowledge of how to handle them safely and effectively.

How a Bullet Comes Out of a Gun

When a gun fires, the primer ignites the powder charge and the burning/expanding gas pressure drives the bullet down the barrel. The rifling puts a spin on the bullet, which keeps the bullet pointed in the same direction during flight, increasing accuracy. Rifling consists of spiral cuts in the bore. The raised parts of the rifling are called grooves, and the lands are the ridges of metal between the grooves.

What “Caliber” Means

Part of knowing how semi-automatic pistols work is understanding bore and bullet sizes. “Caliber” describes the size of a handgun bore and the size of the bullets designed for various bores. Caliber is usually measured as the diameter of the lands in the bore and expressed in hundredths of an inch, thousandths of an inch, or millimeters. For example, a .357-caliber handgun bore measures 0.357 inches in diameter. There are no standards established for designating caliber, which can make things confusing. In some cases, caliber is given as the diameter of the bullet or something close in size to the bore diameter or bullet diameter.

However, every pistol is designed to fire a specific cartridge. Be sure that the ammunition matches the data stamp on the firearm, and follow the manufacturer’s specifications regarding power rating. For example, some sturdier pistols can fire +P ammunition, which is loaded for more power. Lesser designs can’t handle this more powerful ammunition without damaging the gun.

Basic Components of Semi-Automatic Pistols

All modern handguns have three basic groups of parts: trigger group, frame, and barrel.

The trigger group contains the component parts that fire the cartridges. The frame is a metal housing that might also serve as the handle (grip) of the handgun. It contains the trigger group. The barrel is the metal tube through which the bullet travels. Of course, a handgun barrel is much shorter than a rifle or shotgun barrel because the gun is designed to be shot while being held with one or two hands rather than being placed against the shooter’s shoulder. The term “action” can describe the function of the weapon, or as a noun, describing the specific part of a gun.

Repeating handguns (revolvers and semi-automatics) hold more than one round of ammunition. A revolver uses a cylinder to store the ammunition, while a semi-automatic pistol uses a removable magazine inserted into the grip.

The term “pistol” is another point of confusion. Some assert that it describes the action type—that is, a distinction between the terms pistol and revolver—maintaining they are two handgun types. To clear things up, the term pistol describes any weapon designed to be fired with one hand. The word “pistol” is the primary handgun category, with revolvers being a descriptive subset of pistols.

Semi-Automatic Pistol Slides & Magazines

Semi-automatic pistols have reciprocating slides that move back and forth while the barrel stays relatively motionless. The travel of the slide chambers cartridges from the magazine and extracts loaded cartridges or fired cases from the chamber.

Some of the earliest semi-automatic pistol designs have magazines that don’t detach from the gun, such as the Mauser C96. Most modern semi-automatic pistols use a detachable magazine, however. This allows users to carry several preloaded magazines for rapid reloading. Semi-automatic pistols with detachable magazines incorporate a latch, button, or lever that releases the magazine so it can be removed. Two of the primary advantages of semi-automatic pistols over revolvers are the speed of reloading and the increased ammunition capacity.

What “Action” Means for Semi-Automatic Pistols

All firearms have an action type, which is the group of moving parts that control the firing and operation. Semi-automatic pistols also incorporate several action types, including single-action, double-action, striker-fired, double-action-only, and double-action/single-action. Those are the most common action types, although some might expand the list.

A novice might conclude that double-action means a gun can shoot two ways, or make similar assumptions about other action types. The simplest way to determine the action type is to see how many actions occur when the trigger is pulled. If the trigger only releases a pre-cocked hammer, the gun is a single action. But, if pulling the trigger simultaneously draws the hammer to the rear and releases it, firing the gun, it’s a double action. However, if both actions are possible—cocking the hammer manually or pulling the trigger and drawing the hammer to the rear—it’s a double-action/single-action.

Internal striker-fired pistols are the most modern designs. The firing pin is partially cocked when the slide is drawn back, and it’s fully cocked and released when the trigger is pulled.

Handgun Safeties

Manual safeties on semi-automatic pistols can take several forms. Some pistols incorporate multiple safeties, but others only use a passive two-part lever embedded in the trigger. The oldest safety designs include a lever on the rear of the frame or slide. Additionally, some safety levers act as decocking devices, too.

Grip safeties can also be part of the design, whereby the shooter has to squeeze the grip to depress the safety before firing. The Colt Model 1911 has a grip safety as one of its three safety mechanisms. The others are the thumb safety and the hammer itself, which must be cocked before firing.

A cautionary note about safeties: Some models include a key-lock safety to prevent unauthorized people from firing the pistol. These can malfunction from the wear of firing and leave the owner with a gun that won’t work. Additionally, some models incorporate an internal safety that gets engaged when the magazine is removed. The downside to that design is it typically makes the trigger press harder and less smooth.

Alright, now that you know how semi-automatic pistols work, you can more confidently head to the range.