Semi Automatic Pistols

Colt Combat Commander

A semi automatic pistol, semi auto for short, is a magazine fed handgun that uses some of the energy from the fired round to extract the empty case, chamber a new round, and often cock the pistol.

Most often the magazine is in the grip, but other locations have been used.

The less powerful pistols (mostly .22 rimfire) operate on the blowback principle.  In this case the breech does not lock and is held closed only by a spring.  When the gun is fired the rearward movement of the empty casing forces the breech block back against its spring, starting the cycle. The momentum of the breech block fully compresses the spring. Then the spring drives the breech block forward again completing the cycle.

More powerful pistols have a locking breech. In this case the breech remains closed long enough for the high chamber pressure to subside in order to prevent damage to the gun and injury to the shooter. There are several mechanisms to accomplish this but the most famous, and most copied, is the Colt model 1911 designed by John Moses Browning.

In this design the barrel is locked to the slide, which is integral with the breech block. When the pistol is fired the barrel and slide/breech block move rearward together, still locked, This allows time for the chamber pressure to drop. Then a toggle link (or a cam or a ramp in similar designs) unlocks the barrel from the slide. At this point the slide continues to move to the rear while the barrel stops.  The empty case is extracted and the spring closes and locks the slide again.

An excellent animation of this process.

Beretta 92G

Is It Loaded?

A semi auto without a round in the chamber cannot be fired unless the action is worked to strip a round from the magazine and chamber it. Never the less, I would consider a semi auto to be loaded if the magazine contained any live rounds. A gun with a live round in the chamber is also a loaded gun even if the magazine is empty or absent.

  • Keep the pistol pointed in a safe direction!
  • Keep your finger off the trigger!
  • To check the magazine, locate the magazine release and remove the magazine. Inspect the magazine for cartridges.
  • Pull the slide back slightly and inspect the chamber for a live round.

The magazine release is often a button on the left side of the frame forward of the grip, near the trigger guard. On some pistols the button can be swapped to the right side. Others are ambidextrous. The release might be at the bottom of the magazine, or part of the trigger guard. Read the manual.

How To Unload

  • Keep the pistol pointed in a safe direction!
  • Keep your finger off the trigger!
  • Remove the magazine.
  • Pull the slide all the way back and lock it open. Any chambered round will eject.
  • Inspect the chamber to be sure there are no live rounds present.

Note: You must do this in the correct order. Magazine out, then slide back. Otherwise, you risk ejecting one round only to chamber another if the slide goes forward again.

How To Load

  • Insert rounds in the magazine.
  • Insert the magazine in the pistol. Be sure it latches.
  • If the situation warrants, work the slide to chamber a round. Add one more round to the magazine if desired.
  • Lower the hammer or engage the safety.

See states of readiness for a discussion of various conditions in which firearms can be placed.

To Fire

  • Keep your gun pointed in a safe direction!
  • Keep your finger off the trigger!
  • Do not let your hands get in front of the muzzle!
  • If there is not already a round in the chamber, pull the slide all the way to the rear and let it fly forward. This will strip a round from the magazine and chamber it. Do not try to be gentle. It is designed to work this way.
  • When you fire keep your hands below the level of the slide! The slide is going to move to the rear at a high rate of speed. You don't want the skin off your knuckles along for the ride.

In double action mode:

  • Keep your finger off the trigger.
  • Aim at your target.
  • Move your finger to the trigger.
  • While holding your aim, increase pressure on the trigger until the hammer cocks and the gun fires. This will take pounds of force. The recent trend seems to be ten pounds.
  • Move your finger off the trigger.
  • When the round is fired the slide will almost instantly move to the rear, ejecting the empty case. The hammer will also be cocked unless the pistol is double action only. The slide will then fly forward stripping and chambering the next round. The pistol is now ready to fire again. For pistols capable of single action operation, all subsequent shots will be in single action mode because the slide cocks the hammer. Obviously double action only pistols can only be fired in double action mode.

In single action mode:

  • Keep your finger off the trigger.
  • Pull the hammer back to full cock.
  • Aim at your target.
  • Move your finger to the trigger. Caution: In single action mode the trigger pull will be lighter (easier to fire).
  • While holding your aim, increase pressure on the trigger until the gun fires.
  • Move your finger off the trigger.
  • When the round is fired the slide will almost instantly move to the rear, ejecting the empty case and cocking the hammer. It will then fly forward stripping and chambering the next round. The pistol is now ready to fire again.

Not all double action semi autos can be fired in single action mode. Those that can't are called double action only or DAO.

How To Lower The Hammer

Some semi autos have a de-cocker. A de-cocker is a device that will lower the hammer without firing the gun. Other pistols require releasing the hammer with the trigger. Read the manual.

Obviously if the hammer drops on a live round the gun will fire. The hammer must be lowered in a controlled manner while pulling the trigger, or with the de-cocker. Mechanisms can fail. Keep your gun pointed in a safe direction at all times!

If your gun does not have a de-cocker, put a thumb or finger of one hand under the hammer, while pulling the trigger and controlling the hammer with the other hand. Ease your finger out and let the hammer down gently. Keep the gun pointed in a safe direction at all times!

If you don't need to lower the hammer on a live round, it is better to unload the pistol before lowering the hammer.

Single action revolvers.

Double action revolvers.

Return to Firearm Actions.