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Title:	GUN, SUBMACHINE -  U.S. SUBMACHINE GUN UD M42 .45ACP SN# 7
Maker/Manufacturer:	SWEBILUIS, CARL G.
Date of Manufacture:	1940-1941
Eminent Figure:
Catalog Number:	SPAR 1674
Measurements:	OL: 81.9CM 32 1/4" BL: 27.9CM 11" 9.12 lbs. unloaded; 10 lbs. loaded.

Object Description:

U.S. SUBMACHINE GUN UD M42 .45ACP SN# 7
Manufactured by Marlin Firearms, New Haven, Ct. - The High-Standard Sub-Machine Gun Caliber .45 is a blow-back operated, air-cooled, magazine-fed, self-loading shoulder weapon, designed to deliver either semi-automatic or full-automatic fire. 6-groove rifling; right hand twist. Muzzle velocity 1312 fps. Aperture, adjustable for elevation and windage rear; blade front sight. Cyclic rate of fire 880 rpm. Weight of weapon empty is approximately 8.36 and 9.66 lbs. with fully loaded magazine. Blued finish. Wood butt and foregrip. Designed by Carl G. Swebiluis of High Standard and with patents assigned to them, but in fact manufactured by Marlin. Marlin manufactured about 15,000 of these weapons. Complete with 20-round detachable box magazine.

Markings:
Frame: MADE BY/HIGH STANDARD CORP./NEW HAVEN, CONN./PATS. PENDING.
SEMI AUTO SAFE AUTO around select switch.
Receiver: 7.
Barrel: 45 CAL.
Magazine: THE SEYMOUR PRODUCTS CO./SEYMOUR, CONN.

Notes: "It was designed in the years immediately preceding World War II by Carl G. Swebiluis founder of High Standard, with the patent filed October 15, 1940, assigned to High Standard. The gun was manufactured in limited quantities (with total figures being slightly over 15,000 by the Marlin Firearms Company in New Haven, Connecticut for the United Defense Supply Corporation, a United States Government corporation....all know production weapons were produced in 9-mm Parabellum, but some early 'tool room' samples were produced in caliber .45 ACP....The caliber .45 weapons were made as one of the (somewhat late) contenders for the submachine gun intended to replace the THOMPSON in the United States Military. According to military records, this model was first informally submitted by High Standard Manufacturing Company to Aberdeen Proving Ground in late August, 1940. On the basis of good test results, a second model with recommended modifications was submitted in November 1941, for formal testing.
The recommended improvements that were incorporated included a larger (40-round) magazine of the double 20-round, back-to-back style used with the later M. '42 model. This weapon proved reliable and accurate, and was easily controlled in test. In addition, it performed excellently in the mud and dust tests, requiring only wiping of the chamber to get back into action after the mud immersion. By this period, however, the M2 submachine gun had been designated a 'substitute standard,' and the simplified models of the THOMPSON were becoming available, so upon a 'no requirement' report from the Infantry Board, the Cavalry Board, and the Armored Force Board, the caliber .45 UD tests were halted. It is reported that only six weapons in caliber .45 ACP were submitted to various testing boards, and it is doubted if many over this number were produced in the heavy caliber." - Thomas B. Nelson

"There was one other submachine gun manufactured in the United States during World War II. None were issued to the American Armed Forces during the war, but the weapon was supplied to several allied countries during the war. It was also an item of issue to the OSS for use in various clandestine-related operations. The M42 was invented by Carl Swebilius, who was affiliated with the firm of High Standard. High Standard developed the prototype and produced a few early versions of the weapon, but the Marlin Firearms Company manufactured approximately 15,000 of these guns.
Most of these guns were chambered for the 9mm cartridge but a few .45 ACP versions were made as well. The M42 could accept a conventional box magazine and also had the ability to be used with staggered side-by-side magazines.
Government records indicate that 2,405 9mm Marlin MD42 submachine guns were air-dropped in France from January to October of 1944 for use by OSS-related resistance operations.
The UD42 was an unremarkable submachine gun with no outstanding virtures or glaring vices. Since it was not an issue item to U.S. armed forces, it is a little known weapon today and extremely few surviv
"The UD M42, designed by Carl Swebiluis (who had been responsible for the redesign of the Colt 'potato digger' for Marlin), was made only in small quantities - perhaps 15,000 all told - in both 9mm Parabellum and .45-inch ACP. There are stories of it being the preferred weapon of the clandestine Office of Strategic Services, and of it turning up in the hands of partisan groups, particularly those fighting the Japanese." - Roger Ford

"The development models and prototypes were made by High Standard, but the production (of about 15,000) was by Marlin....The UD (United Defense) M42 was rather more complicated than the normal run of submachine guns, but it was very well made from good material and it performed well in adverse conditions. It was unfortunate in appearing just after the Thompson had gained official approval, and so it never achieved a major contract. The gun fired from an open bolt and the firing pin was operated by a hammer as the bolt closed. The bolt handle was unusual in being a slide which did not move with the bolt and acted as a shutter to seal the boltway against dirt. A .45 version was made, in an attempt to interest the US Army, but with the Thompson M1 in ample supply the army reported 'no requirement' and the design lapsed." - Hogg & Weeks

"...Marlin's problems with the M2 could not be blamed on lack of experience on their part, since they were, at that time, completing a contract for another submachine-gun, the United Defense Model 42. This had been designed prior to the war by Carl Swebilus of the High-Standard Manufacturing company, well known for their target pistols, and was patented in October 1940. It was offered to the US Army in .45 calibre and favourably reported on, but at that time the simplified Thompson M1 was being perfected and the Army was unable to justify a second design. It was then demonstrated to the British and Dutch governments. The British considered that the design needed further development, but the Dutch were sufficiently impressed with it to order 15,000 guns in 9-mm Parabellum calibre. Marlin received the contract and produced the guns, but where they ever went to is a minor mystery of the war. Some certainly went to Java for the Dutch, before the Japanese invasion, and it is understood that some went via the SOE and OSS to various European resistance and partisan groups, but beyond that little is known.
The UD M42 was a well-made weapon in the production form, operating in the usual blow-back system, though it is one of the select few in which the differential locking system was abandoned. The bolt was closed and stopped by the time the round was fired, the firing pin being operated by a swinging hammer which came into action by striking a fixed plate in the receiver as the bolt closed. Another unusual feature was a hold open device operated by the magazine platform. This ensured that after the last shot in the magazine had been fired, the bolt was held back as an indication to the firer. A common enough feature in automatic pistols, this was rare in submachine-guns." - Ian Hogg

"U.S. Government records indicate that 2,405 9x19 mm Marlin M42 submachine guns were air-dropped in France from January to October of 1944 for use by OSS-related resistance operations." - American Rifleman, July, 1998.

References:
Brophy, William S. MARLIN FIREARMS. A HISTORY OF THE GUNS AND THE COMPANY THAT MADE THEM. Stackpole Books. Harrisburg, Pa. 1989.
Canfield, Bruce N. U.S. INFANTRY WEAPONS OF WORLD WAR II. Andrew Mowbray Publishers. Lincoln, R.I. 1994.
Ford, Roger. THE GRIM REAPER: MACHINE GUNS AND MACHINE GUNNERS IN ACTION. Sarpedon Press. N.Y., N.Y. 1996.
Hogg, Ian. THE COMPLETE MACHINE GUN: 1885 TO THE PRESENT. Exeter Books. N.Y., N.Y. 1979.
Iannamico, Frank. UNITED STATES MACHINE GUNS: FROM THE AMERICAN 180 TO THE ZX-7. Moose Lake Publishing LLC. Henderson, NV. 2004.
Nelson, Thomas B. THE WORLD'S SUBMACHINE GUNS (MACHINE PISTOLS). Vol. I. T.B.N. Enterprises. Alexandria, Va. 1977.
U.S. Army Ordnance. SUBMACHINE GUNS
Notes on Material - DESCRIPTION OF HIGH STANDARD CAL..45 SUB-MACHINE GUN. January, 1942.