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Title:	GUN, MACHINE -  U.S. MACHINE GUN T45 .60 SN# 54
Maker/Manufacturer:	GENERAL ELECTRIC
Date of Manufacture:	1946-1953
Eminent Figure:
Catalog Number:	SPAR 6560
Measurements:	OL: 75" BL: 53 1/2"

Object Description:

U.S. MACHINE GUN T45 .60 SN# 54
Manufactured by General Electric, Burlington, Vt. - The T45 gun is an electrically operated, multi-barreled, caliber .60 machine gun, designed for handling belted electric primed ammunition at speeds up to 4,000 rounds per minute. The gun is driven by a 24-volt d. c. drive motor. The associated solenoids required a 24-volt d. c. power supply and a firing circuit, a minimum of 250 volts d. c. power. No separate charger is required. The T45 consists of a rotating firing mechanism with six 60-inch barrels. The weapon will operate satisfactorily with caliber .60 electric-primed ball ammunition belted by means of T44E4 links. Model A-10. 6-barrel, motor driven MG based on Gatling system. Muzzle velocity 3,000 fps. Rate of fire 4500-5000 rpm. Firing rate: 4,000 rounds/minute at 568 revolutions/minutes and 24 volts at motor. Suggested maximum safe firing time (continuous burst): 7 seconds. Dispersion: 3 to 4 mils (80% circle). Weight of gun 477 pounds with 6-60" barrels. Only 10 T45s were made.

Markings:
Etched on: LOW TEMP/FLY WHEEL/A10
Tag once attached to electric drive of weapon placed in catalog folder. Tag reads: DRIVE, ELECTRIC/FOR GUN, AUTO/T45 MOD 10 #54/(MUSEUM}. Reverse side: NOTE - RETURNED/FROM ROY L./SANFORD ON/25 NOV. 56.

Weapon listed as overage found on post in Museum area and accessioned into Army collection. Army# was 6936 and is now 7388. Weapon transferred to the Museum on 25 July 1956 (Refer to C-6M-M16). Weapon at that time appraised at $2500. Weapon listed as missing on ROS of 1959. Serial number of this weapon is listed as 54. This is being referred to as a Model A-10.

ARMORY HISTORICAL REPORT - 2 SEPTEMBER 1945 THRU 1 JULY 1951 - "Weapon, Aircraft, Multi-barreled, T45 - To design and develop a multiple barrel aircraft machine gun having a rate of fire of 6000 rpm (1000 rpm in each of 6 barrels); an external power drive; a weight of approximately 350 lbs; and overall length of either 80" or 52"' and firing electric primed ammunition."
1JUL51 - 31DEC51 - "The development of a multiple barrel gun, driven by an external power source, and having a rate of fire of approximately 6000 rpm (1000 rpm in each of six barrels) by the General Electric Company during this period continued and improvements in design, evaluation of existing designs and the manufacture of models for test and evaluation is continuing with delivery dates scheduled for February, June and August 1952. Springfield Armory worked with The Autoyre Co. and Roy S. Sanford & Co. in the development of links essential to this weapon. Testing of the A4 Model Caliber .60, T45 Gun continued with 1551 rounds being fired at Quabbin Range. Because of a gun jam due to failure to extract and double feed, only limited firing was possible. The damage caused by the gun jam was chiefly a broken cam, two bolt assemblies and the high voltage connector."
1JAN52 - 30JUN52 - "General Electric and Lockheed Aircraft Corporation continued work on the development of Cal..60 and 20mm multiple barrel guns. Difficulty was experienced with breakages of various components and feeder trouble but good gun functioning of the Cal..60 T45 was obtained at the General Electric range after modifications have been made. Two 20 MM T156 gun barrels modified to simulate T171 gun barrel conditions were tested at Quabbin Range. Indications from this test showed that reduction of weight of the T171 barrel is possible....
At Purdue Research Foundation, work continued on bore and in-wall temperature measurements and calculations, with the electronic thermal analyzer, of barrels for the T130 Machine Gun. Tests were conducted as to how far barrels for the T45 and T171 could be lightened without sacrificing stiffness and strength. Progress continued toward the design of a machine to straighten barrels and a means to measure their straightness. Investigation continued in an effort to find a faster and more accurate method of drilling gun barrels....
Work continued on an effort to convert the Cal..60 multi-barreled gun to fire 27 MM ammunitio1JUL52 - 31DEC52 - "Because of oil failure or lack of oil, the 'A7' Model Gun at Lockheed jammed. Tests were performed at Springfield Armory in the Climatic room to determine optimum oils for use in all model guns. Development work on the 'C' model continued and excessive metal, removed from certain castings, reduced the weight by approximately 20 pounds. Approval of award for the fabrication of 'D' model guns was received and studies were begun to lighten this model through fabrication of components using Titantium steel."
1JAN53 - 30JUN53 - "Four T45 Guns were completed by General Electric Company."
1JUL53 - 31DEC53 - "Delivery of Caliber .60 T45 and T45E1 multi-barreled weapons was completed at General Electric Co. and design and test work was discontinued in favor of the 20mm versions of these weapons."

Notes: "Gun, Machine, Caliber .60 T45. Motor-driven machine gun with several barrels based on the Gatling system developed by the General Electric Co. under the supervision of the Ordnance Corps. Rate of fire 6,000 rounds per minute. Weight of gun approximately 427 pounds with 60-inch barrels....
Advantages of the T45 Gun. Advantages of the external power driven gun over the normal type of gun mechanism are: 1. No gun charger is required and gun stoppage does not result from misfires, round being extracted automatically. 2. As gun mechanism does not start and stop at each cycle and uncontrolled reciprocating parts are eliminated, the resulting impact loads occurring in normal type guns are eliminated, the resulting impact loads occurring in normal type guns are eliminated. The majority of gun failures are caused by impact. 3. The use of springs is reduced to a minimum. Failure of gun springs subjected to repeated impacts at high frequencies is one of the main troubles with standard type guns. 4. As the belt of ammunition is not subject to the repeated starting and stopping occurring in standard type guns, the belt is not subject to separations." - Chinn, Vol. III

"Richard J. Gatling's rotating, multiple barrel design, patented over three quarters of a century earlier in 1862, contained the promising features that could be modernized to obtain the new up-to-date needs of a very high firing rate with sustained, reliable fire power. In fact, in 1893 it was demonstrated in a very simple test that a Gatling Gun could be fired at up to 3000spm (shots per minute) using an electric motor and belt to drive the Gatling's crank.
This proved correct when in 1949 General Electric started testing the first model of its new Vulcan Guns. This gun was the T45 (Model A). It fired calibre .60 ammunition and fired at about 2500 shots per minute from its six barrels being driven by an electric motor.
Although this first gun was heavy and the firing rate was low, it provided technical data as a firing bed for improved design and performance that was to follow.
The T45 proved again that the Gatling principle of rotary motion eliminated gun bolt buffers which caused extremely high impact, accelerations, and was the gun design of the future. The T45 proved that the earlier planned requirement of 600 spm firing rate with greater parts life and fewer malfunctions were correct and could be attained. There were test firings of 10 guns that included flight tests on an F-94 at Elgin Air Force Base and firings at the Springfield Armory, at Aberdeen Proving Grounds and at Wright Patterson Air Force Base.
The problem that were recognized and had to be refined included excessive weight, high drive power to accelerate the gun to full rate in 0.4 seconds, ammunition capability for firing electrical primers, weak ammunition belts, and links, larger storage containers, barrel cluster integrity and heating, gun clearing after each burst, gun feeding and case ejection and gun bolt lock stiffness.
A new contract was signed with General Electric to work out these problems with a new design gun. The new gun was t
"In the early 1890s, Gatling Guns with electric motores were experimented with by the U.S. Navy and other interested parties. With an electric motor, Dr. Gatling was able to fire at rates approaching 1,500 rounds per minute. This high rate of fire was not needed at the time and the electric Gatlings were soon dispensed with. Both ordnance engineers in the 1940s remembered these experimental weapons. In early 1946, a Model 1903 .45-70 Gatling Gun borrowed from a museum was set up with an electric motor drive and test-fired. The 90-year old design reached speeds of 5,000 rounds per minute for a short time.
Further studies of the action determined the Dr. Gatling's original operating principles could reach even higher rates of fire than the tests had already proved. In June 1946, a contract was issued to the General Electric Corporation to design a weapon based on the Gatling multibarrel design that would reach a minimum rate of fire of 1,000-rounds-per minute per barrel.
The designs were studied and worked on for several years. In the interim time, several designs parameters were changed including adding another barrel to the original five-barrel requirement. A firing model of the new T45 was ready by April 1949. The prototype fired at rate of 2,500 rounds per minute for short times. Further work resulted in fire rates of 4,000 rounds per minute by June 1950. By 1952, the original caliber of the weapons, an experimental .60 caliber round, was changed to 20 millimeters. The new 20mm gun multibarrel was to be identified as the T171E1.
Thirty-three 20mm T171E1 weapons were produced by General Electric between 1953 and 1955. The T171 weighed in at 365 pounds and fired 20mm ammunition at a rate of 4,000 rounds per minute. Further design changes geared toward a production weapon were incorporated in the new model, the T171E2, in 1954. Problems with the breech were incorporated in the new model, the T171E2, in 1954. Problems with the breech of the T171E2 resulted in more changes to stiffen certain portions of the weapon. In April 1956, the T171E3 had been completed which had all the improvements of the earlier designs. Developments of the new weapon was considered complete by December 1956 and production was begun at a low rate. By December 1957, the T171E3 was designated the M61 Vulcan cannon and production speeded up." - Dockery

References:
Chinn, George M. THE MACHINE GUN. Vol. III. Department of the Navy. Washington, D.C. 1953.
Chinn, George M. THE MACHINE GUN. Vol. V. Edward Bros. Publishing Co. Ann Arbor, Mi. 1987.
Dockery, Kevin. WEAPONS OF THE NAVY SEALS. Berkley Books. N.Y., N.Y. 2004.

See, SA-MR20-2175 - CALCULATION OF THE VOLUME OF EXHAUSTED POWDER GASES FOR SMALL-ARMS WEAPONS. 30 November 1950.
SA-MR20-2176 - CALCULATION OF THE POWER DEVELOPED BY AUTOMATIC GUNS OF VARIOUS CALIBERS. 4 December 1950.