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Title:	GUN, MACHINE -  U.S. MACHINE GUN T17E3 AIRCRAFT .60 SN# 77915
Maker/Manufacturer:	ROCK ISLAND ARSENAL
Date of Manufacture:	1945
Eminent Figure:
Catalog Number:	SPAR 2766
Measurements:	OL:130.1CM 51 1/4" BL:

Object Description:

U.S. MACHINE GUN T17E3 AIRCRAFT .60 SN# 77915
Manufactured by Rock Island Arsenal, Rock Island, Il. - The T17E3 machine gun consists of a receiver supporting a cover, breech ring and barrel. Within the receiver slide a bolt and bolthead. In the cover is a cam tube with a helical slot cut in it. Riding within the cam tube, guided by a helical slot, is the drive bushing which encloses one end of a drive spring. On the outside of the cam tube near its forward end is cut a spur gear which engages the rack that operates the feeding mechanism. When the cover is closed, a stud on the drive bushing engages a raised portion of the bolt and in operation the bolt, bolt-head, and drive bushing travel together. The firing pin is fastened in the front of the bolt and projects into the bolthead. The charger retracts the drive bushing which in turn pulls the bolt back to the sear which is located at the rear of the receiver. When the sear is released, the bolt goes forward, and the bolthead is rotated and locked by the cams on the breech ring and bolt. As the bolt head rotates, the bolt moves forward in relation to the bolthead. This causes the firing pin to protrude, ready to fire the primer. A buffer spring and a buffer plate are mounted in the buffer block at the rear of the receiver. This assembly arrests the rearward movement of the bolt assembly and with the assistance of the drive spring returns the bolt assembly to battery during automatic fire. This gun weighed 135 pounds including recoil mounting adapter, electrical charger and solenoid and feed mechanism. The rate of fire was 600 rounds per minute, the muzzle velocity was 3,500 feet per second. The gun was 92 inches long and had a maximum trunnion reaction of 3,500 pounds. Barrel missing.

Markings:
Receiver: U.S. NO. 77915R GVT. INSP./MACHINE GUN CAL. 60 T717E3/MANUFACTURED BY ROCK
ISLAND ARSENAL. V/FR-1054-.
Belt housing: 07160326-12 RIA. 4 in pencil.

Weapon listed as overage found on post in Museum area and accessioned into Army collection. Army # was listed at 6876. Army number is now 7377. Weapon was originally transferred to the Museum as Army # 6876 on 31 March 1955. At that time weapon was appraised at $800. This weapon was listed as missing on ROS of 1959.

Notes: "Gun, Machine, Caliber .60 T17. In September 1942, a project was initiated to convert the 15-mm German aircraft gun, MG 151, a recoil-operated. air-cooled, and belt-fed gun, to use the caliber .60 cartridge. In October 1942, Colt Patent Fire Arms Manufacturing Co. undertook this conversion. The gun was designated Caliber .60 Machine Gun T17. It was found necessary to rechamber the barrel, lengthen the receiver, feedway, bolt, cam tube, and cover, and to make a few other minor design changes. New links were provided by the Autoyre Co.
Gun, Machine, Caliber .60 T17E1. The Frigidaire Division of the General Motors Corp., Dayton, Ohio, undertook in January 1943 to provide 10 pilot models of the aircraft machine gun, caliber .60 T17E1. The model was to be essentially the same as the T17, except that the rate of fire was to be increased to 800 rounds per minute and the high trunnion reactions were to be lowered by incorporating in the design a recoil adapter developed by the Edgewater Steel Co. at the request of the ordnance officer at Wright Field. Links for the gun were developed by the Autoyre Co. of Oakville, Conn. Complete drawings of the T17 gun were prepared by Frigidaire and an engineering study was made to redesign the weapon for cheaper mass production.
Gun, Machine, Caliber .60 T17E2. The Frigidaire Division was then asked to prepare two additional models which would use strengthened components and a barrel with a thicker walled chamber as the chamber had expanded during tests of earlier models. SAE 1060 steel was used in the T17E1 wherever possible. In the T17E2 this policy was abandoned and SAE 4060 steel was substituted. Fabrication of these models involved the use of sheer metal stampings and hydrogen brazing. The gun was designated the T17E2. In May 1943 the General Electric Co., Bfunctioned fairly satisfactorily with a rate of fire of 600 rounds per minute. The second gun with with the General Electric charging mechanism was fired 143 rounds. A combination gun was built from parts of guns No. 1 and 2 and fired 327 rounds at 658 rounds per minute and a maximum velocity of 3,696 feet per second. Numerous malfunctions were encountered which indicated that considerable further developments work was needed.
Gun, Machine, Caliber .60 T17E3. Beginning in September 1943, attention was concentrated upon the manufacture of seven T17E3 guns with both percussion and electric ignition. On 15 December 1943 this order was increased to 10 guns. The electrical ignition mechanism was modeled upon the German 20-mm gun. A program was also initiated for the development of a bolt with the sear forward. It was expected that this, together with electrical ignition, would permit synchronization of the gun with either electrical or percussion primed ammunition was used. On 16 November 1943 Frigidaire was requested to develop four auxiliary gun chargers to be used as a standby device in case of failure of the electric charger. Because of a requirement placed with the Ordnance Department by the Navy Bureau of Ordnance for delivery of 2,500 caliber .60 aircraft machine guns with auxiliaries and spare parts in 1944, limited procurement of the T17E3 was initiated 2 December 1943 and approved 16 December 1943. Rock Island Arsenal was commissioned to make these guns. This gun weighed 135 pounds, including recoil mounting adaptor, electrical charger and solenoid, and feed mechanism. The rate of fire was 600 rounds per minute, and the muzzle velocity was 3,500 feet per second. The gun was 92 inches long and had a maximum trunnion reaction of 3,500 pounds. At the request of the Army Air Forces the original procurement was increased to 5,025 guns by Ordnance Committee action on 23 December 1943." - Chinn

LIMITED PROCUREMENT PROGRAM - By June 1944, Rock Island Arsenal, through the Industrial Service, had been furnished complete drawings for the Caliber .60 T17E3 Machine Gun and all accessories as developed up to that time except the bore cooling device. Tooling at Rock Island Arsenal as approximately 80 percent completed. Every effort was made to cooperate and assist Rock Island Arsenal in this tooling and to modify components and assemblies and simplify design to assist manufacture. The weekly meetings were almost entirely devoted to this work. Rock Island Arsenal had completely assembled three Caliber .60 T17E3 Machine Gun from parts made at the Arsenal and by its sub-contractors. These guns were test fired approximately 100 rounds each. Ammunition did not feed properly. The cam tube was redesigned by Rock Island Arsenal to a two-piece contruction without prior firing tests. This was not satisfactory as the forward locking end became separated from the remainder of the tube. This was corrected by Rock Island Arsenal as soon as observed. Further firing tests disclosed that these guns fired erratically with a cyclic rate of approximately 600 rpm. Frequent bolt head and breech ring breakages were encountered. Rock Island Arsenal breech rings failed at an approximate average of 1,000 rounds each with Frigidaire breech rings were failing at approximately 5,000 rounds average life. Later, one Frigidaire breech was fired more than 20,000 rounds. Difficult extraction was encountered with frequent breakge of extractors. As a result of this performance, manufacturing operations were reduced. On 15 August 1944, at the invitation of this Office, Navy, Rock Island Arsenal, and Industrial Servired another Frigidaire-manufactured gun 2,138 rounds wihtout a malfunction. An intensive development study was initiated to correct the differences between the Frigidaire Division and Rock Island Arsenal manufactured gun.

References:
Chinn, George M. THE MACHINE GUN. Vol. III. Department of the Navy. Washington, D.C. 1953.

SA-MR1-5001 - SALVAGING OF LINER MATERIAL FROM CALIBER .60 MACHINE GUN BARREL ASSEMBLIES, S. Wallen, 2 November 1948.
SA-MR1-5002 - TESTS OF CALIBER .60 BARREL ASSEMBLIES WITH STRENGTHENED RETAINERS, V. Luukonen, 15 November 1948.
SA-MR1-5004 - TESTS TO DETERMINE EFFECT OF HOLE THROUGH LINER WALL IN CALIBER .60 BARREL ASSEMBLY, V. Luukkonen, 30 June 1950.
SA-MR1-5005 - TEST OF CALIBER .60 BARREL ASSEMBLIES HAVING PRESSED OR COINED FLUTED CHAMBERS, S. Caloccia, 28 July 1950.
SA-MR1-5006 - ENDURANCE TEST OF SHORTENED BARRELS IN THE CALIBER .60 T17E5 MACHINE GUN, A. Fowler, 7 November 1950.
SA-MR1-5007 - TEST OF CALIBER .60 BARREL ASSEMBLIES WITH LINERS OF 'CODE HL' MANUFACTURED BY 'CODE HK', D.G. Hondros, 20 March 1951.
SA-MR1-5008 - TEST OF CALIBER .60 BARREL ASSEMBLIES WITH LINERS OF 'CODE HM' ALLOY MANUFACTURED BY 'CODE HK', D.G. Hondros, 16 February 1951.
SA-MR1-5009 - TEMPERATURE RISE OF BEARING SURFACE OF CALIBER .60 BARREL ASSEMBLY, N.W. Martin, 23 February 1951.
SA-MR1-5011 - TEST OF CALIBER .60 BARREL ASSEMBLIES WITH LINERS OF NO. 25 'CODE HL' MANUFACTURED BY 'CODE HK', D. Hondros, 20 July 1951.
SA-TR1-5000 - PARTIAL REPORT ON SPECIAL U-SHAPED CHAMBER FLUTES IN CALIBER .60 MACHINE GUN BARRELS, V. Luukkonen, 16 February 1948.
SA-TR1-5003 - FINAL REPORT ON FIRING TESTS OF GAIN TWIST RIFLED, CALIBER .60, AC, MG, BARRELS COMPARED TO STANDARD BARRELS, S. Wallen, V. Luukkonen, 17 December 1948.