U.S. M1911 and M1911A1 Colt Automatic Pistol, -45 A.C.P. Caliber

Oct 24, 2026

Guide describing the U.S. M1911 and M1911A1 Colt Automatic pistol, its development and service history with .45 A.C.P. ammunition, and how it operates as a magazine-fed, recoil-operated, single-action semi-automatic firearm. Includes part identification lists for the M1911 and an interior cutaway for the M1911A1, then explains post-1924 refinements mapped to numbered illustrations. Provides a practical manual of arms covering carry, inspection, drawing, loading, aiming, firing, and returning the pistol safely.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

Overview

Design and service history

M1911 major components

M1911A1 modifications

Manual of arms

Carry, inspection, draw, and return

Raise and load

Aim and fire

U.S. M1911 and M1911A1 Colt Automatic Pistol, .45 A.C.P. Caliber The first automatic, magazine-fed pistol adopted by the U.S. Army, the Colt M1911 is a single action, semi-automatic, recoil-operated pistol chambered for the .45 caliber A.C.P. (Automatic Colt Pistol) cartridge. With the gas of fired cartridges driving back the slide to eject the spent cartridge casing, the pistol was self-loading from a box, spring-fed magazine holding seven rounds inserted and locked in the pistol’s handle. Adopted to replace the M1892 .38 caliber Colt Revolver, the Automatic Pistol’s powerful .45 cartridge proved lethal in stopping power against Moro guerillas in the Philippines. Designed by John Browning, the Colt Automatic became an iconic pistol of the U.S. military, carried through twentieth century wars until the Baretta M9 9mm Pistol was adopted in 1985. Nevertheless, the M1911 is still carried into combat by many American troops as their pistol of choice, in personal preference to the official M9 sidearm. Manufactured in large numbers for service in the trenches of the Great War, the Colt Automatic was supplemented by revolvers for the American Expeditionary Force: the M1917 Colt or Smith and Wesson .45 caliber revolvers chambered for the A.C.P. cartridge loaded in “half moon” metal clips inserted into the pistol cylinders to ease ejection of fired cartridge casings. Redesigned in 1924 with slight modifications to the original design (most parts interchangeable between the models), the Colt .45 Automatic (M1911A1), was the primary service pistol of the U.S. Army, Navy, and Marines by World War II. Besides the U.S. Armory manufactured pistols, contractors like Colt, Union Switch and Signal, Remington-Rand, and Singer produced Colt Automatics for war service. M1911 Colt 1. Hammer. 2. Right Hand Stock (Walnut, with “Diamonds”). 3. Trigger. 4. Slide. 5. Ejector Port. 6. Front Sight. 7. Slide Stop. 8. Magazine Catch. 9. Safety Lock. 10. Rear Sight. 11. Grip Safety. 12. Stock Screw. 13. Plunger Tube (inside: a. Slide Stop Plunger; b. Plunger Spring; c. Safety Lock Plunger). 14. Lanyard, Pistol. 15. Magazine, M1911, with Lanyard Loop. 16. Magazine Pouch. M1911A1 Cut away drawing of interior parts. After 1924, the M1911 Pistol saw various modifications as the M1911A1. These improvements to the original design updated the reliable WW1 sidearm for WW2 (and beyond) use. Describe the refinements to the pistol illustrated below: the numbers serve as hints to the modifications. 1. Trigger cut back and knurled on face. 2. Clearance cuts each side of frame at trigger. 3. Grip safety tang lengthened. 4. Shortened Hammer. 5. Mainspring housing curved. 6. Wood grips changed to plastic (Bakelite) without “diamonds. 7. Front sight ramped and squared. 8. Rear sight changed to square notch. Magazine with lanyard loop replaced with flat base. Parkerized finish replaces original bluing. Lanyard loop remains on butt. The pistol remained virtually the same through its service life. With modern modifications, the .45 pistol is still preferred by soldiers for stopping power over the M9 (itself now replaced by the Sig Sauer XM17, also in 9 mm). MANUAL OF ARMS The movements of the pistol drill differ from that of the rifle in that there is no need for simultaneous execution. The drill consists of movements for the simple, quick, and safe handling of the pistol. Pistol is carried in a holster fastened to the Mills waist belt. Magazines are carried in the pouch attached to the belt. Inspection, Pistol. Draw pistol from holster and hold upright in right hand, muzzle inclined upward at 30°, finger outside of trigger guard. Always hold pistol with barrel oriented in safe, downrange direction. Insure hammer is in safe (down) position. Visually inspect pistol for magazine: if inserted, turn pistol slightly to right, press release catch with right thumb, and remove magazine from handle with left hand. Insure magazine is empty of cartridges

FAQs

What cartridge does the M1911 chamber, and how does its feeding work?

The M1911 is chambered for the .45 A.C.P. (Automatic Colt Pistol) cartridge and uses a spring-fed box magazine holding seven rounds.

What are the M1911A1 improvements mentioned after 1924?

The text describes trigger and frame clearance cuts, grip safety and hammer changes, mainspring housing shape, and updates such as changing wood grips to plastic, adjusting sights, magazine base form, and a Parkerized finish.

What key safety steps are required before firing the M1911?

It notes three safety locks/settings: the thumb-operated slide lock safety, the grip safety, and the half-cock hammer safety, and that all must be disengaged to fire.

Oct 24, 2026

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