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Title:	GUN, MACHINE -  U.S. MACHINE GUN T197 TANK .30 SN# 1
Maker/Manufacturer:	SPRINGFIELD ARMORY
Date of Manufacture:	1954
Eminent Figure:
Catalog Number:	SPAR 2670
Measurements:	OL: 86.9CM 34 1/2" BL: 55.8CM 22" 26 lbs.

Object Description:

U.S. MACHINE GUN T197 TANK .30 SN# 1
Manufactured by Springfield Armory, Springfield, Ma. in 1954 - Pre-production model of the M73 tank machine gun. Based on the design of Russell Robinson. Specific aim was to produce weapon with short inboard length. Short recoil operation with gas assist. Utilized a horizontal sliding breechblock. Left of right hand feed. Quick change barrel. Muzzle velocity 2760 fps. Cyclic rate of fire 500-550. Weapon weighs approximately 26 lbs.

Markings:
Receiver: T-197 T.M.C./CAL.30 NO.1. Etched on mounting block: 1.

Weapon transferred to the Museum on 5 January 1965. At that time weapon was appraised at $7,000.

HISTORICAL SUMMARY OF ACTIVITIES:
1JAN53 - 30JUN53 - Detail drawings were completed on the T197 and T199."
1JUL53 - 31DEC53 - "Function fire tests and engineering studies continued on the T197 guns at the Armory to improve weapon reliability and to overcome undesirable effects....
Proposals were received for a feasibility study of converting the Caliber .30 T197 Tank Gun into a Caliber .50 version and it was anticipated that Armour Research Foundation would do the work."
1JAN54 - 30JUN54 - "The No. 1 Model T197 was satisfactorily test fired through 8,000 rounds. Failure to eject was the major problem to be overcome. The No. 2 model was reworked to include the latest modifications that were incorporated in the No. 1 model. A design of an improved lightweight version of the T197 Tank Gun was initiated."
1JUL54 - 31DEC54 - "Development study and engineering test continued on the No. 1 Model of the T197 Caliber .30 Tank Machine Gun with new improvements being made on the feed cam for smoother feeding, the backplate sear, and a stellite-lined chrome-plated barrel. Layout drawings of a lighter weight model were nearly completed."
1JUL55 - 31DEC55 - "Two models for the T197 Tank Machine Gun were being fabricated by Bellmore-Johnson Tool Company for use at Detroit Arsenal in conjunction with tank engineering studies. Delivery was scheduled for 30 March 1956. A program was outlined and submitted to Ordnance Weapons Command which would provide for development of either the T197 singly or the T197 and the T198 weapon to the point of providing a limited number of weapons for user tests."
1JAN56 - 30JUN56 - "Two T197 models were fabricated to the 1953 design for use of Detroit Arsenal. These models were scheduled for rework at the Armory to incorporate improved components that were incomplete when the project was suspended in 1953. This project was reactivated in April 1956. Two existing T197 (1953) test models were modified and reworked for design engineering study and test. Test evaluation study indicated that interference were present in the feed mechanism, rammer and recoiling components. These prototype models were used in redesign study to overcome existing deficiencies. The improved model version was designated as T197E1 and the estimated completion date for a set of drawings was scheduled for October 1956. Drawing of the T197E1 model was about 25% completed. The estimated date for test of the T197E1 models was December 1956. Contract action was initiated to procure six solenoids with packard type terminals. The standard M2 ground mount must be modified for use with the T197E1 gun and a design study was scheduled for initiation by 15 August 1956. Two mount models were scheduled for fabrication design and engineering evaluation. The above program effort was scheduled commensurate with allocated funds."
1JUL56 - 31DEC56 - "Progress was made for a smoother functioning model of the T197 by improving the feeding of belted ammunition, case ejection and rammer cartridge feed travel. Studies were completed to improve conditions of exhaustive toxic gases within a tank and tests incorporating the features of two systems fabricated were scheduled for tests at Aberdeen Proving Ground."
1JAN57 - 30JUN57 - "Two T197 .30 Tank Machine Guns were completed in February, one Model E1 and one Model E2. Late in the period, the remaining 16 guns on this order were released for fabrication and Design improvements on this weapon have resulted in smoother cam feed, improved downward control of spent cases, stronger holding pawls, and use of front barrel bearing and jacket. Toxic tests conducted at APG indicated test gas accumulation was no more severe than the M37 weapon with M2 ammunition. Fabrication of sixteen T197E2 models have been initiated. Concurrently, development effort is continuing to improve reliability of function, feed, extraction and ejection: increased component life, and reduction in rate of fire."
1JAN58 - 30JUN58 - "Eighteen T197E2 Guns were delivered during this period, with an order for twenty additional guns received in May and scheduled for March 1959 delivery....
Fabrication of 16 sets of components was completed. Retrofit effort on the spare parts was 75% completed. Additional spare parts were ordered to support User Tests at Arctic Test Base and Yuma, Arizona.
Two models each, were subjected to engineering function fire tests at APG and the Armory. Function fire was generally satisfactory in normal role. Several components were broken and new parts were made for replacement. Several minor deficiencies were corrected to improve function in adverse climatic tests and at -65 degrees F. A front barrel removal design feature was fabricated and tested through 3,000 rounds. Four additional models were completed in June and forwarded to USAAB, Ft. Knox for User Tests along with spare parts and three spare barrels for each gun.
Design improvements were completed on the following components: charger mechanism, front bearing, case ejector, cover, closing cams and back plate."
1JUL58 -31DEC58 - "Twenty-two of these guns were fabricated and will be delivered to Research and Development Division early in 1959. Again, the Armory's work load made it necessary to procure approximately 70% of the parts, with the Armory making assemblies. Features requested as the result of user tests, and those found necessary in Research and Development tests, will be incorporated in these guns.
A production engineering study is being conducted on this weapon in cooperation with the Engineering Division and Research and Development Division. This division's phase of the study is scheduled to be completed during the last half of the FY 1959. Date complied in this study will be used to review the weapon design for producibility and cost, and to prepare a detailed cost estimate...."
Four guns were functioned fired tested at Springfield Armory and Aberdeen Proving Ground through 10,000 rounds each. Several broken components were encountered and redesigned for longer life and smoother function. Models Number 11 and 12 of the T197E2 were tested at Aberdeen in November 1958 to determine the concentration effects of toxic gas, carbon monoxide. The radially slotted front bearing booster was better than the elongated slotted booster. The test guns were placed in a sealed chamber with an opening simulating the M48 tank condition. Earlier tests indicated that the carbon monoxide gas effects in the T197 were no more severe than with the standard M37 tank gun. The accepted Ordnance level of the toxic gas, carbon monoxide concentration is 0.01 per cent by volume in a gas tank turret.
Four additional weapons were tested by User Services at Fort Knox, Kentucky. Bearing and barrel performance was improved by redesign to permit continuous firing through 3000 rounds without cleaning bearing booster. Further design improvements were completed on the following components and/or actions: round carrier, barrel lock, buffer alignment, solenoid self locking lever nut, firing pin extension, sear contact, lock plate, cover lock means, chain hand charger, less trigger pull and smoother cam feeding function. The above action was initiated to overcome existing deficiencies by the User Services at Fort Knox.
Tests wereComprehensive link redesign to meet free hinging, ease of belt assembly and disassembly in the field, and ease of ammunition storage in tan contained continued. Fifty thousand links were made and tested to prove design improvement. About 500 of these links were informally demonstrated at the User Service Boards, USAIB, Fort Benning and USAIB, Fort Knox. Additional quantities made from production tools were available for formal tests at the above Service Boards pending results of engineering listed below at Aberdeen Proving Ground.
Ten thousand links were engineering function fired tested in the T197E2 tank gun by the Armory and performance was satisfactory. Five thousand links were forwarded to Aberdeen Proving Ground for additional engineering tests. Several million M13 type links were ordered from the Jackes-Evans Manufacturing Co. in St. Louis, Missouri."
1JAN59 - 30JUN59 - "In February, the Armory was notified of Crash Programs for the M60 Tank which included in its armament a 7.62mm machine gun and a .50 Cal. machine gun. Higher headquarters indicated that a requirement for 900 each of these weapons. Even though the T197E2, 7.62mm Tank Machine Gun and the T175E2 Cal..50 Tank Machine Gun were undergoing User Tests and had not been Type Classified, they were selected for use on the M60 Tank Program. Estimates were submitted which included 12 month and 17 month initial deliveries of these weapons. During the period up to 30 June 1959 the quantities of the weapons to be fabricated were indefinite, ranging from 900 down to 180 each per T197E2 and T175E2, respectively, have been received and $1,950,000 authorized for each gun program. The Armory's estimate for this T197E2 program (Type Classified as M73) was $3,651,000 and the estimate for the same T175E2 gun program (Type Classified as M85) was $7,500,000.
The initial deliveries of the M73 gun based upon the receipt of order are scheduled for June 1960. The initial deliveries of the M85 gun are scheduled for October 1960.
The T175E2 or M85 gun is a weapon which is designed to accept a newly conceived disintegrating belt link known as the M15 which replaced the T98 link used on the T175E1 gun....
Order for pilot line manufacture of 188 M73 weapons was received in May 1959, calling for initial weapon delivery in May 1960. Production engineering study of this weapon was begun....
OTCM 37060 dated 14 May 1959 approved type classification of the T197E2 model as the M73 Tank Machine Gun, Standard Type A. A complete set of R&D drawings and technical data were transferred to Product Engineering Division for the preparation of standard Ordnance drawings.
Research and Development Division placed a fabrication order with Armory Operations Division for 180 M73 guns destined for tank installation.
Four Model Nos. 15, 16 (SPAR-2647), 17 (SPAR-2653) and 18 (SPAR-2646) were tested by USAAB at Fort Knox. Heavy carbon fouling was observed in the booster bearing at 3,000 rounds. Two component breakages (the breech block roller stud and the pin for grip round carrier) were evaluated as having too short a service life. The two parts were improved and new components were successfully tested through 20,000 rounds each at Springfield Armory.
Two new T197E2 guns Nos. 40 (SPAR-2656) and 41 were function test fired at Fort Knox for test data on carbon fouling in the bearing booster and on the service life of critical components.
Two guns, Nos. 42 and 47, with the latest retrofit features, were shipped in June to Aircraft Armaments1JUL59 - 31DEC59 - "The user tests of the T175E1 gun and T98 link were completed during this period with unsatisfactory results. The M85 weapon and M15 link are expected to overcome the problems encountered.
Fabrication of one cover to accept the M15 link was accepted."

References:
SA-MR3-1800 - EVALUATION STUDY OF THE ROBINSON, CALIBER .30 TANK MACHINE GUN, by R. Colby. 4 December 1952.
SA-NM3-1903 - NOTES ON DEVELOPMENT TYPE MATERIEL FOR THE CHAIN CHARGER FOR T197E2, CALIBER 7.62MM TANK MACHINE GUN-Addendum to 301902, A. Meyer, P. Marshall, 3 Nov. 1959.