By Frank Iannamico
When the United States entered World War II, many U.S. infantrymen were issued the semiautomatic caliber .30 M1 rifle. The armies of other nations involved in the conflict, both Allied and Axis, were generally issued bolt-action rifles whose designs were basically pre World War I technology. The Russians and Germans did field semiautomatic service rifles but their issue was rather limited.
As the war in Europe was nearing its end the Germans began to field their select-fire, 7.92×33 midrange assault rifles. Fitted with a 30-round magazine, the German soldier carrying the new Sturmgewehr was well equipped for engagements at either close or extended ranges. Although the weapon was less powerful than the U.S. M1 rifle, it gave the German soldier not only a semiautomatic weapon, but also the option of full automatic fire. During 1945, the United States introduced its own select-fire weapon: the M2 carbine. Like the German weapon, the M2 was fed by a 30-round box magazine; the only disadvantage of the M2 was its somewhat anemic cartridge. The primary disadvantage of a select-fire .30-06 M1 rifle concept was its enbloc eight-round clip, which severely limited its effectiveness as a full-automatic weapon.
Springfield Armory’s Rifle, Caliber .30, T20
When the Infantry Board formally requested an automatic version of the M1 rifle in September of 1944, the Ordnance Department responded by informing them that they had already begun to develop a select-fire version of the M1 rifle back in May of 1944. The select-fire M1 under development at the Springfield Armory was designated as the T20 rifle. The first T20 select-fire M1 rifle was delivered to Aberdeen Proving Ground in early November 1944. The weapon’s select-fire operation was achieved by means of an independent sear release actuated by a connector operating off of a cam located on the operating slide. The T20 design attempted to use a closed bolt operation for semiautomatic fire and an open bolt for automatic fire. Other problems plagued the T20 rifle. Due to extreme heat generated by automatic fire, the wooden foregrip would get hot enough to char during extended firing. Excessive recoil generated by the powerful .30 caliber cartridge also proved to be a major problem. To aid in control of muzzle rise, John Garand designed a series of muzzle brakes. Though they proved effective in controlling muzzle climb, there were several problems with John Garand’s designs. The first muzzle brake design required a redesigned gas cylinder lock, and with that device installed on the barrel a bayonet or a grenade launcher could not be used on the rifle. Subsequent T20 variations had redesigned muzzle brakes that did permit the attachment of a bayonet or grenade launcher.
Remington Arms’ Rifle, Caliber .30, T22
A separate contract had been awarded to the Remington Arms Company to concurrently develop a select-fire version of the caliber .30 M1 designated as the T22. There were two Remington prototypes designated as the T23 and T24, which oddly preceded the T22 design. The T23 and T24 were M1 rifles designed to test Remington’s ideas for a select-fire weapon with both rifles using the M1’s eight-round enbloc clip. The T23 used a fire control arrangement based on an independent hammer release system. The T24 version used an independent sear release system to achieve automatic fire from the M1. Both rifles were sent to the Ordnance Department for evaluation who then tabulated the results of their testing and passed them on to Remington for incorporation into the T22 rifle. Some of the desired features listed in Remington’s contract were: have select-fire capability, be equipped with a folding bipod, folding buttstock, the ability to launch grenades and have a magazine with a capacity of twenty rounds. The proposed weapon with all of the aforementioned features was to weigh no more than nine pounds. The standard issue M1 rifle weighed 9.5 pounds unloaded. The folding stock requirement was later dropped.
Remington Arms’ version of the select-fire M1, the T22, was also shipped to Aberdeen for testing. Both the T20 and T22 rifles far exceeded the original nine pound weight requirement. When the rifles were fired in the full-automatic mode they both operated from an open-bolt position. Magazine problems with both rifles were encountered. To ensure the consistent feeding of cartridges, an extremely strong magazine spring was required though it was feared such a strong spring would damage the cartridge follower. Another problem was the retention of the magazine’s floorplate, which would be difficult with a stiffer follower spring. Rather than attempt to redesign the magazine, John Garand addressed the problem by lengthening the receiver just .3125-inch. The alteration allowed for much better cartridge feeding, but would require a newly designed receiver, thus the idea was briefly rejected. The Aberdeen testing did prove that a select-fire rifle using the Garand’s basic M1 action was workable. There were modified versions of the Remington design designated as the T22E1, which featured an improved magazine release and bolt hold-open device and the T22E2 that incorporated an improved trigger group, gas cylinder, muzzle brake and bipod. Remington’s T22 series were originally favored by the Ordnance Department because the design readily lent itself to modifying existing M1 rifles during a rebuild program. The end of World War II terminated all of Remington’s work on the M1 rifle, while the Springfield Armory would continue its research and development.
One of the major challenges facing the personnel attempting to develop a select-fire M1 was that they were limited to only minor design changes. Any major redesigns would hamper the current production process of the M1, which was considered critical to the war effort.
Rifle, Caliber .30, T20E1
The T20E1 design was a direct result from the testing of the T20 and T22 designs. The T20E1 fired both semiautomatically and automatically from a closed bolt. To address the overheating problem, two heat flow arresting grooves were machined into the barrel at the chamber to aid in heat dispersion. The receiver of the T20E1 was further modified to simplify the operation of locking the receiver and trigger group together as well as introduce a more secure means of locking the box magazine in place. The T20E1 also had a recoil check at the muzzle, although the design could mount a bayonet, it could not accommodate a grenade launcher. A new redesigned magazine replaced the problematic modified BAR magazine used with the T20 rifle. The T20E1 also featured a bipod mounted onto the gas cylinder, but it was not readily removable from the weapon. The T20E1 was tested at the Ordnance Research Center at Aberdeen from 22 through 26 January 1945. The few problems encountered were several failures to feed; this was traced to the bolt-bearing surface in the barrel, which was determined to be too soft. Several minor improvements and changes were authorized and the Springfield Armory was instructed to assemble 100 rifles with the suggested modifications. This was to be the definitive select-fire version of the M1 Garand rifle designated as the T20E2.
Rifle, Caliber .30, T20E2
The T20E2 rifle differed from the T20E1 mainly by the use of the elongated M1 receiver designed by John Garand, a bolt modified with a roller lug for ease of feeding and extraction of cartridges, recoil check design, which permitted the use of a flash hider and a new type of grenade launcher or a bayonet. The T20E2 could fire either semiautomatically or full automatic with a cyclic rate of 700 rounds per minute. The T20E2 weapon was fitted with a bipod, muzzle device and a detachable telescopic sight. Full automatic fire was achieved by a connector assembly, which was actuated by the movement of the operating rod handle. In turn, a sear release or trip was actuated, which with the trigger held in a rearward position, disengaged the sear from the hammer lugs immediately after the bolt was locked or in-battery position. With the connector assembly disengaged, the rifle could only be fired semiautomatically and functioned in a manner similar to that of the M1 rifle. The twenty-round box magazine was redesigned so that it could be used in the Browning Automatic Rifle, but the standard BAR magazines could not be used in the T20E2 rifle. The receiver bridge of the T20E2 was modified to incorporate an operating rod lock to facilitate cooling or cleaning. The magazine latch was designed to allow one-hand removal of empty magazines. The automatic connector and connector springs were riveted together to form a single unit with the addition of a connector spring guide and the lengthening of the operating spring guide.
The weapon greatly exceeded the initial nine pound weight requirement with a loaded weight of over 12.5 pounds. The M1 based T20E2 was tested and considered sufficiently developed to place into production. In May of 1945, the T20E2 was designated as a Limited Procurement Type. At a meeting held on 17 May 1945, the Ordnance Technical Committee recommended the urgent procurement of 100,000 T20E2 rifles. Although the war in Europe had ended, the United States anticipated the invasion of the Japanese homeland. Expecting very high casualties, the U.S. wanted the invasion troops to have the most individual firepower the Ordnance Department was able to provide them. The war ended before any of the rifles could be produced and delivered. However, the conclusion of the war did not end the development of the T20 rifle series. Scant post-war funds merely slowed the work down, and with the war now over, time was no longer an issue. There was a variation of the T20E2 modified for the T65 cartridge (later adopted the 7.62 NATO round). Upon close examination of the T20 series of select-fire rifles, many similarities that were later implemented into the 7.62 U.S. M14 Rifle, adopted in 1957, can be readily seen.
U.S. Rifle, Caliber .30 T20E2
Operation: Gas, select-fire
Automatic operation: 700 rounds per minute
Rifle Weight: unloaded, without accessories: 9.63 pounds
20-round magazine weight: empty: .55 pounds; loaded: 1.69 pounds
Grenade launcher: .47 pounds
M1 Bayonet: 1.0 pound
Overall length: 44.88 inches
Barrel length: 23.7 inches,
Rifling: 4-grooves, right hand twist, 1:10
|This article first appeared in Small Arms Review V10N5 (February 2007)