1943 Union Switch & Signal
SN - 1,050,399

Union Switch & Signal company of Swissvale Pennsylvania, primarily made railroad signaling equipment but received a contract on May 5, 1942 for the manufacture of 200,000 M1911A1 pistols.  The first pistols were accepted by Ordnance inspectors in January 1943, but the company received word that their contract would be canceled, due to a severe drop in requirements for the pistol.  Within a month U.S.&S. had signed a contract to supply carbine parts. On March 8, 1943 the company was officially notified that their contract had been cut back from 200,000 pistols to 30,000 pistols.  However on June 26th, when the contract was nearly complete, and many of the workers had been transferred to Carbine operations, the company received a letter of intent to purchase an additional 25,000 pistols.  The last of the pistols was shipped on November 27, 1943.  55,000 Union Switch and Signal pistols were delivered serial numbered from 1041405 to 1096404 with peak production reaching 650 pistols a day.   

U.S.&S. pistols are the second rarest of the M1911A1s (55,000 produced), only the Singer is rarer (500 produced).  None of the Union Switch & Signal 1911A1s have the crossed cannons ordnance stamp even thought the practice was standardized in late 1942. Also most of the early pistols up through about serial 1060100 received no “P” proof on the slide and frame.  From about 1060100 to about 1082000, the “P” proof was applied, but at the Left edge of the slide where the curved part meets the flat.  This was due to a poorly drawn ordnance drawing showing the placement of the proof.  From about 1082000 to the end of production, the “P” was placed in its normal location on the top of the slide (center in front of rear sight).  When the "P" proof mark is found it will be on both the slide and receiver and be of the same size. Notice the "P" proof stamp is smaller then Colts but still an uppercase letter.

The number of different machining operations performed by US&S on the parts for the pistol, was 600. These required the services of 658 different machines; 421 types of cutting and drilling tools; 239 different fixtures, and 447 different gages. While the Government owned the machines, gages and fixtures, US&S provided its own perishable tools. The receiver for each pistol underwent 106 individual operations, during which some four fifths of its weight was machined from the original forging.

Another interesting fact is the development of the US&S firing range, the design of which was later adopted by various pistol manufacturers including Colt. On the range each of the 55,000 pistols produced was test fired 21 times. Not a single pistol manufactured and assembled by US&S was rejected by the resident ordnance department inspector, of the 55,000 pistols fired by the US&S inspector before being passed to the Government Inspector, only two failed in one test. They were found to be completely automatic in action, firing seven shots with one trigger pull. US&S was consistently rated high in tests for Interchangeability of parts.  The test was conducted once a month, the four producers of the pistol being required to send six pistols each to the key inspectors of the small arms pistol industry integration committee. The pistols were taken apart, the parts scrambled, and the 24 pistols re-assembled.

It is reported that Union Switch & Signal produced high quality pistols and did not experience the extreme production problems that Remington Rand and Ithaca had. The ordinance department reported the Union Switch & Signal pistols had a superior finish and consistently rated high in the interchangeability tests. According to the Springfield Research database a lot of these pistols were shipped to the Navy and the OSS.

This early example has the P on both the slide and receiver which is unusual. It was not acceptable for one reason or another and sent to the Salvage Crib to correct the malfunction.  This happened to many pistols, and is only noticeable on this one because of the late date of adopting the P.  There were so many, for example Ithaca sometimes had 10% or more, they became backlogged and often took several weeks or longer to get repaired depending on the severity of the problem.  By the time this pistol was submitted or resubmitted for acceptance the P proof mark had been adopted.  This pistol is a very collectible oddity .

It may have been the pistol was held back due to problems with the slide or disconnector that US&S had in early production. The slide had a maximum tolerance allowed in the diameter of the drilled barrel hole on the slide of .002". This was a special problem because the steel was hard to machine. This piece had a total of 94 operations in all performed on it. Manufacture of the disconnector suffered because of inadequate gaging procedure. Inspection requirements on this piece later were changed by the Ordnance Department. In any case it makes this a very unique early specimen in outstanding 99% condition.   Reference Charles Clawson's “Colt .45 Service pistols”, various Government and US&S documents and correspondence with C.W. (Chuck) Clawson. Click on images for larger versions.

Right profile

Left profile

RCD Inspectors and proof mark

A standard and
 EXP model pistol

Bottom view

Property and Model markings

Legend, Trigger, and Slide Stop

Rear sight, hammer, and Proof mark

Thumb safety and feed ramp

Front sight

Slide stop

Slide firing pin hole


High Standard Barrel

Barrel bushing


  • Barrel is made by High Standard

  • Front Sight is serrated

  • Rear sight is square notch

  • Trigger is short, stamped, and many where blued

  • Safety and slide lock where checkered.

  • RCD is the Inspectors mark, Lt. Col. Robert C. Downie
    (Located below slide lock)

  • Of the approximately 1100 workers employed in production of the pistol, about 1000 were women.

From the T. Moore collection