U.S. Rifles

(Updated 15 February 2012)

.30 Caliber Rifle T20

Notes Early in 1944, Springfield Armory initiated the development of the first model of the T20 rifle, incorporating full and semiautomatic fire. Full automatic fire was accomplished by an independent sear release. The model was capable of automatic fire from an open bolt and semiautomatic fire from a closed bolt position. The open bolt feature did not adequately solve cook-off problems. The basic principle of operation was considered satisfactory. Development of the T20 model terminated in January 1945 with recommendations that minor design changes and strengthening of various components be made. A rifle incorporating these minor design changes was designated T20E1.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T20E1

References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T20E2

Notes: In early 1945, the T20E2 rifle was developed from its predecessors, the T20 and T20E1 rifles. This rifle could be fired either on a full or semiautomatic basis. Full automatic fire was achieved by a connector assembly which was actuated by the operating rod handle. This, in turn, actuated a sear release or trip which, with the trigger held to the rear, disengaged the sear from the hammer lugs immediately after the bolt was locked. This model included a recoil check on the muzzle. The bolt was modified to ease feeding and extraction The receiver was slightly longer than that of the M1 rifle. This allowed the bolt to travel further to the rear and improve feeding. This model also had a gas port located approximately 1 1/2 inches from the muzzle. The T20E2 rifle was designated Limited Procurement Type in May 1945. The project was terminated in March 1948.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T22

Notes: The T22 rifle development was begun in early 1944 by the Remington Arms Company. In this design effort, full automatic fire was accomplished in the open bolt position and semiautomatic fire from a closed bolt position. The open bolt feature did not effectively prevent cook-off. The T22 project to modify the M1 rifle was terminated in March 1948.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T22E2

Notes: The T22E2 rifle was developed from its predecessors (T22 and T22E1) by Remington Arms Company. Full automatic fire was accomplished in the open bolt position; semiautomatic fire was accomplished from a closed bolt position. This model incorporated a slight change in the trigger group to simplify manufacture as well as an improved magazine catch. The major advantage of the T22E2 was in its adaptability to re-manufacture of M1 rifles as a peacetime operation. This project was terminated in March 1948.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T23

Notes: This rifle was a modification of the M1 rifle to provide full and semiautomatic fire. Automatic fire was to be provided by an independent hammer release. The T23 model was advantageous from the standpoint of design, durability, and minimization of functional stresses. Because of mechanism timing, this model fired fully automatic from an open bolt approximately 20 percent of the time. Tests of this weapon indicated the desirability of firing from the closed bolt position. The tests also indicated that a new magazine should be designed rather than attempt to modify the BAR magazine. A device designed to increase gun stability during automatic fire was definitely needed. The project was terminated in March 1948.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T24

Notes: The T24 rifle was also a modification of the M1 rifle to provide full and semiautomatic fire. Automatic fire was provided by an independent sear release. This project was initiated simultaneously with the T23 rifle development in October 1944. This model fired full automatic from a closed bolt position at all times. This project was also ended in March 1948.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Lightweight Rifle T25

Notes: The T25 rifle was the first of the new lightweight rifles to fire the improved T65 type ammunition. This project was initiated in September 1945. This model was designed for selective semiautomatic or full automatic fire. Full automatic fire was performed in the open bolt position. The front sight mount and the bayonet lug were integral with the flash suppressor as a separate unit from the gas system components. The gas cut-off system and front-end design were eventually incorporated into the T44 rifle. The project was suspended in November 1951.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T27

Notes: The T27 rifle project, initiated in April 1946, modified the M1 rifle to fire the new improved .30 caliber ammunition (7.62mm NATO). The rifle was capable of selective full and semiautomatic fire. This project was terminated in March 1948.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Lightweight Rifle T28

Notes: This program initiated in October 1946 was to design a lightweight, selective full and semiautomatic weapon to replace the M1 rifle, M2 carbine, M3A1 submachine gun, and the BAR. This rifle, with an in-line stock, was designed to explore the feasibility of low-cost fabrication techniques. Complex stampings and simplified forgings were used extensively in this design. This mechanism had insufficient structural rigidity for satisfactory function and durability. The breech mechanism was an adaptation of an experimental Mauser design. The trigger mechanism was also of German origin. Development of this rifle was suspended in late 1950.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Lightweight Rifle T31

Notes: The T31 rifle development program was begun in March 1947. This weapon was a lightweight, selective full and semiautomatic rifle with an in-line stock. It was also intended to replace the M1 rifle, M2 carbine, M3A1 submachine gun, and BAR. This model was a novel approach to infantry rifle design and had unusually low stripping forces and energies. The magazine design was later incorporated into the T44 rifle. Attempts were made to reduce recoil and eliminate flash and muzzle blast. These attempts were unsuccessful and the development program was suspended in late 1950.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Lightweight Rifle T33

Notes: This rifle development program was initiated in March 1949. This rifle was developed on the initiative of a private inventor with guidance from the Office, Chief of Ordnance. The project was suspended in late 1950 because the weapon lacked sufficient ruggedness and durability.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Lightweight Rifle T35

Notes: The T35 rifle development program was initiated in June 1944. This rifle was a modification of the M1 rifle designed to fire the new and improved caliber .30 (7.62mm) NATO ammunition. This semiautomatic weapon incorporated a drop wood stock, iron aperture rear sight, and post front sight. This particular development was suspended in the latter part of 1950.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Lightweight Rifle T36

Notes: A lightweight rifle modified from the T20E2 rifle was officially designated the T36 rifle in November 1949. This weapon was designed to fire the 7.62mm NATO ammunition. The T36 rifle could be used in both full and semiautomatic fire from a closed bolt position. It had a drop wood stock, iron aperture rear sight, and post front sight. A modified T25 rifle magazine design was incorporated into this model. This magazine functioned very satisfactorily. Further modification included a one-piece hand guard and a special butt plate. The T36 rifle development was terminated in the latter part of 1950.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Lightweight Rifle T37

Notes: The T37 rifle was a lightweight rifle modified from the T20E2 and incorporated features from the T36 rifle. This rifle fired NATO ammunition in both the full and semi-automatic roles. The important modifications included a lightweight 22-inch barrel with the gas port approximately four inches from the muzzle and a lightweight wooden stock. The design included the T20E2 receiver but with filler blocks fore and aft of the magazine. Further revisions incorporated a lightweight stabilizer/flash suppressor and a bolt buffer. Following tests, recommendations were made for further development of a lightweight rifle that would be manufactured with existing production tools.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T44

Notes: The T44 rifle, an eclectic model, evolved from a modified T37 rifle with a gas expansion-cutoff system. This weapon included the front end components of the T25 rifle, the breech system and magazine catch mechanism of the T20E2 rifle, and the magazine of the T31 rifle. This rifle, with a lightweight barrel (1.8 pounds), was developed to replace the M1 rifle, M2 carbine, and the M3A1 submachine gun. It was capable of selective full or semiautomatic fire. It had a prong type flash suppressor together with an automatic pressure relief valve for grenade launching. The bolt action was similar to that of the M1 rifle. Full consideration was given to utilization of tooling used in the manufacture of the M1 rifle.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T44E1

Notes: In October 1951, a heavy barrel (3.5 pounds) version of the T44 rifle was fabricated and designated as the T44E1 rifle. This rifle was designed to replace the BAR. It featured a rate reducer that could provide dual rates of automatic fire. The heavy barrel feature was designed to reduce weapon jump and to withstand the greater heat and increased erosion that would result from automatic fire. This weapon also had a hinged butt, two position bipod, and a new flash suppressor unit.

.30 Caliber Rifle T44E2

Notes: Modifications to the lightweight barrel version of the T44 rifle led to a weapon which was designated as the T44E2 rifle. It utilized a short receiver and a gas impingement system. Front magazine latching and a centrally activated bolt catch were incorporated. A new operating rod with a modified cross rail section, a new bolt, trigger housing, trigger guard, and a grenade launcher with reduced gas volume were also included in this design.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

7.62mm Rifle M-14 (T44E4)

Type Classified: June 1957
Weight (Fully Loaded): 11 lbs
Barrel Length: 22 inches
Method of Action: Gas operated, air cooled
Maximum Range: 3,500 yards
Maximum Effective Range: 500 yards
Magazine Capacity: 20 rounds
Production:
1,380,264 built from FY58 to FY63 (Total), with a Production Learning Curve of 92%.
   167,100 at Springfield Armory
   356,501 at Olin Mathieson
   537,500 at H&R
   319,163 at TRW
Notes: In October 1954, a new rifle with a lightweight barrel was designated as the T44E4 rifle. It was developed to eliminate the modified components used in the T44 model. In order to fire the NATO ammunition, the bolt, firing pin, connector, stock, and receiver of the rifle were designed with shortened dimensions. An improved bolt catch and magazine were also designed. The automatic pressure valve used in grenade launching was replaced with a manually operated valve. The rifle could be converted to either automatic or semiautomatic fire by removal of the selector lock and installation of a selector. The rifle was also equipped with a prong type flash suppressor. In June 1957, the T44E4 was classified standard as the M-14, replacing the M1 rifle, M2 carbine, and M3A1 SMG.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

7.62mm Automatic Rifle M-15 (T44E5)

Notes: In October 1954, a new heavy barrel rifle was designated T44E5. It was developed to eliminate the modified components used in the T44E1 model. Since this weapon had the identical operating mechanism as the T44E4, it was type classified standard, replacing the BAR, as the M15, 7.62mm automatic rifle in June 1957. The M15 rifle was declared obsolete in December 1959, following successful firing tests of the M14 rifle with the M2 bipod and a slotted plastic upper hand guard.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Rifle T47

Notes: In October 1951, a successor to the T25 model was designated T47. This model had a lightweight barrel and fired both full and semiautomatic from the closed bolt position. The bolt of the T47 rifle was locked and unlocked by the tilting action of the breech lock. This was the chief feature that distinguished it from the T44 rifle. The T44 was considered superior and T47 development program was terminated.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

.30 Caliber Lightweight Rifle T48

Notes: The Belgian FN rifle was designated the T48 by the Ordnance Corps in October 1951. The rifle was converted to fire the NATO ammunition and was ready for user tests late in 1952. The T48 was a lightweight, gas-operated, air-cooled rifle that could be fired both automatic and semiautomatic. It competed against the T47 and T44 rifles during user tests as a possible successor to the M1 rifle. The outstanding feature of this weapon was its ease and speed of field stripping attributed to a hinged receiver resembling that of a conventional break-open shotgun. Its weight was substantially the same as the M1 rifle. In April 1953, tests of the T47 rifle were discontinued. Only the T44 series remained in competition with the T48 FN rifle. The T44E4 was selected as the better rifle in June 1957, terminating further evaluation of the T48.
References:
Technical Report 68-4: M-14 Rifle Cost Analysis Report, U.S. Army Materiel Command (October 1968)

5.56mm Rifle M16

Weight: 6.351 lbs (without magazine and sling)
Length: 39 inches (44.25” with bayonet)
Maximum Rate of Fire (Automatic): 150/200 rpm
Maximum Rate of Fire (Semiautomatic): 45/65 rpm
Maximum Effective Range: 460 meters
Authorized Ammunition:
   5.56mm M193 Ball
   5.56mm M196 Tracer (Red Tip)
   5.56mm M199 Dummy
   5.56mm M200 Blank (Violet Tip)
References:
U.S. Army TM 9-1005-249-10 (M-16/A1 Manual) (February 1985)

5.56mm Rifle M16A1 (XM16E1)

Type Classified: 1967
Weight (Unloaded): 6.55 lbs (without magazine and sling)
Weight (Loaded): 7.6 lbs (20 rd magazine and sling) or 7.9 lbs (30 rd magazine and sling)
Length: 39 inches (44.25” with bayonet)
Rifling: 1 twist for every 12 inches
Selector: SAFE-SEMI-AUTO
Maximum Rate of Fire (Automatic): 150/200 rpm
Maximum Rate of Fire (Semiautomatic): 45/65 rpm
Maximum Effective Range: 460 meters
Authorized Ammunition:
   5.56mm M193 Ball
   5.56mm M196 Tracer (Red Tip)
   5.56mm M862 Plastic Practice Ammunition
   5.56mm M199 Dummy
   5.56mm M200 Blank (Violet Tip)
Notes: You can fire M855 and M856 ammunition in an M16A1 in an emergency, but there is not enough spin imparted on the rounds due to the longer twist ratio, so even in an emergency, you should limit your engagement ranges to 91.4 meters or less.
(Dispersal of M855/856 ammunition in M16A1 slide from FM-23-9 from July 1989 – 100 kb GIF)
References:
U.S. Army TM 9-1005-249-10 (M-16/A1 Manual) (February 1985)
FM 23-9 (3 July 1989)

5.56mm Rifle M16A2 (M16A1E1) (Colt Model 645)

Type Classified: November 1983
Weight (Unloaded): 7.78 lbs (without magazine and sling)
Weight (Loaded): 8.48 lbs (20 rd magazine and sling) or 8.79 lbs (30 rd magazine and sling)
Length: 39.625 inches (44.88” with bayonet)
Rifling: Right Hand Twist, with 1 twist for every 7 inches
Selector: SAFE-SEMI-BURST
Rate of Fire (Semi): 45 rpm
Rate of Fire (Burst): 90 rpm
Rate of Fire (Cyclic): 700-900 rpm
Rate of Fire (Sustained): 12 to 15 rpm
Maximum Range: 3,600 meters
Maximum Range (Area Targets): 800 meters [? Might be a OCR misread of 600]
Maximum Range (Point Targets): 550 meters
Authorized Ammunition:
   5.56mm M855 Ball (Green Tip)
   5.56mm M856 Tracer (Red Tip)
   5.56mm M862 Plastic Practice Ammunition
   5.56mm M199 Dummy
   5.56mm M200 Blank (Violet Tip)
Issuance: USMC
References:
FM 23-9 (3 July 1989)
U.S. Army TM 9-1005-319-20 (M16A2/A3/A4 and M4/M4A1) (October 1998)
The M-16 by Gordon Rottman

5.56mm Rifle M16A3 (M16A2E3) (Colt Model 646)

Type Classified: 1996
Weight (Loaded): 8.79 lbs (30 rd magazine and sling)
Length: 39.625 inches (44.88” with bayonet)
Rifling: Right Hand Twist, with 1 twist for every 7 inches
Selector: SAFE-SEMI-AUTO
Rate of Fire (Semi): 45 rpm
Rate of Fire (Burst): 90 rpm
Rate of Fire (Cyclic): 700-900 rpm
Rate of Fire (Sustained): 12 to 15 rpm
Maximum Range: 3,600 meters
Maximum Range (Area Targets): 800 meters [? Might be a OCR misread of 600]
Maximum Range (Point Targets): 550 meters
Notes: Developed by the US Navy for SEALs, Seabees and security forces. Replaced M-14s as shipboard rifles.
References:
U.S. Army TM 9-1005-319-20 (M16A2/A3/A4 and M4/M4A1) (October 1998)
The M-16 by Gordon Rottman

5.56mm Rifle M16A4 (M16A2E4) (Colt Model 945)

Type Classified: 1996
Weight (Loaded): 8.79 lbs (30 rd magazine and sling)
Length: 39.625 inches (44.88” with bayonet)
Rifling: Right Hand Twist, with 1 twist for every 7 inches
Selector: SAFE-SEMI-BURST
Rate of Fire (Semi): 45 rpm
Rate of Fire (Burst): 90 rpm
Rate of Fire (Cyclic): 800 rpm
Rate of Fire (Sustained): 12 to 15 rpm
Maximum Range: 3,600 meters
Maximum Range (Area Targets): 600 meters
Maximum Range (Point Targets): 550 meters
Notes: Has a detachable carrying handle with an integral accessory mounting rail.
References:
U.S. Army TM 9-1005-319-20 (M16A2/A3/A4 and M4/M4A1) (October 1998)
The M-16 by Gordon Rottman

5.56mm Carbine M4 (Colt Model 920)

Weight (Loaded): 7.5 lbs (30 rd magazine and sling)
Length (Open Buttstock): 33 inches
Length (Closed Buttstock): 29.75 inches
Rifling: Right Hand Twist, with 1 twist for every 7 inches
Selector: SAFE-SEMI-BURST
Rate of Fire (Semi): 45 rpm
Rate of Fire (Burst): 90 rpm
Rate of Fire (Cyclic): 700-970 rpm
Rate of Fire (Sustained): 12 to 15 rpm
Maximum Range: 3,600 meters
Maximum Range (Area Targets): 600 meters
Maximum Range (Point Targets): 500 meters
References:
U.S. Army TM 9-1005-319-20 (M16A2/A3/A4 and M4/M4A1) (October 1998)
The M-16 by Gordon Rottman

5.56mm Carbine M4A1 (Colt Model 921)

Weight (Loaded): 7.5 lbs (30 rd magazine and sling)
Length (Open Buttstock): 33 inches
Length (Closed Buttstock): 29.75 inches
Rifling: Right Hand Twist, with 1 twist for every 7 inches
Selector: SAFE-SEMI-AUTO
Rate of Fire (Semi): 45 rpm
Rate of Fire (Burst): 90 rpm
Rate of Fire (Cyclic): 700-970 rpm
Rate of Fire (Sustained): 12 to 15 rpm
Maximum Range: 3,600 meters
Maximum Range (Area Targets): 600 meters
Maximum Range (Point Targets): 500 meters
References:
U.S. Army TM 9-1005-319-20 (M16A2/A3/A4 and M4/M4A1) (October 1998)
The M-16 by Gordon Rottman

Colt Advanced Combat Rifle (M16A2E2)