Thompson M1a1 Serial Number Database

Duplicate Serial Numbers: Colt manufactured 60,000 pistols in the Ithaca serial number range (804), 41,696 in the Remington Rand serial number range (900), and 4,171 in the US&S serial number range (10896). Ithaca and Remington Rands where not manufactured or shipped in numerical order.

  • Numbers were issued sequentially, beginning where Ordnance had left off with serial number blocks assigned during WWII. The letter X preceding the serial number designated it as a replacement. The new serial number was hand stamped on top of the receiver behind the rear sight, in the vicinity of the prior serial number.
  • Serial numbers are, from front to back, 708, 586,389 & 993. Note the 'first 1000' Aut-ord-Co bullet logo on the top of the receivers. Development of the Thompson SubMachine gun, by Theodore H. This little history was written by Theodore Eickhoff about his experience with John Thompson and developing the Thompson sub machine gun.
  • Operation: M1, M1A1 Semiautomatic Length: 36' Weight unloaded: 5.19 lbs. SERIAL NUMBER RANGE 1,762,520-1,875,039 SAGINAW STEERING GEAR DIVISION (GRAND RAPIDS).

By Frank Iannamico
It took the Auto-Ordnance Corporation nearly twenty years to sell off all of the original 15,000 Thompsons that had been manufactured by Colt. However, in 1939, the German invasion of Poland touched off an unprecedented worldwide demand for weapons, particularly small arms.
In the years following the initial run of the Colt made Thompson, the Auto-Ordnance Corporation, with lagging sales and deeply in debt, fell into the hands of Russell Maguire. In the late 1930’s Maguire had anticipated a major war in Europe, and a demand for weapons. When Maguire obtained the assets of Auto-Ordnance there wasn’t much except for some drawings, prints and a few unsold guns. Maguire at first tried to interest Colt in another production run of the Thompson, but they were already committed to manufacturing other military weapons, and were not interested. Maguire eventually negotiated with the Savage Arms Corporation of Utica, New York to manufacture the Thompson for Auto-Ordnance. In April of 1940, after a twenty-year hiatus, the first Model of 1928 Thompsons were rolling off Savage’s assembly line. The first contract for the new guns was from France, followed by several orders from Great Britain.
These early Savage Thompsons were very much like the Colt 1928 Navy model, featuring a finned barrel fitted with a Cutts compensator, as well as a finely checkered actuator knob, safety and rocker levers. The early Savage guns also featured a vertical foregrip. As per their contracts with A-O, Savage was not permitted to place their name on the Thompsons that they manufactured. The only way to identify a Savage manufactured 1928 or 1928A1 Thompson is by the S prefix on the serial number. All parts manufactured by Savage were also marked with a letter S. Parts manufactured by Savage’s sister plant, J. Stevens, were marked with a block style letter S. Savage and Stevens manufactured virtually every part for the gun except for various screws and springs. All WWII Savage guns were originally assembled at the factory with Savage (S) or Stevens (S) marked parts.
While the Colt Thompsons were blued, the Savage guns were finished by a process called Du-Lite which was a black oxide type III finish. When this finish was applied to a sandblasted surface it had a flat-black appearance. When applied to other surfaces that have not been sandblasted, it had a low luster blue appearance. The outside surfaces of the trigger frames and receivers were sandblasted on Savage Thompsons prior to the Du-Lite finish being applied, resulting in a flat black color. The inside of these components will appear a dull blue color as will the barrel and all other steel parts and components.
The British Contract Savage Model of 1928
The early 1928 Thompson guns manufactured for the British contracts were marked with a very small British inspector’s stamp placed on the receiver and/or the barrel. The guns were purchased directly from the Auto-Ordnance Corporation. The British contract guns were all fitted with the Lyman adjustable rear sight, and a vertical foregrip. The early one-piece flat-machined ejector was fitted to the early guns as well as the early style (2nd design) Cutts compensator. Thompsons fitted with a vertical foregrip came from the factory with only one sling swivel. This swivel was located on the bottom of the buttstock. British armorer’s often relocated the sling swivel to the top of the stock and added a swivel to the side of the foregrip. There were no U.S. or A1 markings on British contract guns. The British purchased 108,000 Thompsons and a large number of spare parts before the enactment of the U.S. Lend-Lease program. In the first contract the British paid $175.00 for each Thompson they purchased, the price was lowered in subsequent contracts. The very early Savage 1928 models shipped to the British had Auto-Ordnance’s New York, NY address roll marked on the left side of the receiver at the rear.
The Savage Commercial Model of 1928
During Savage’s production of the Thompson, the Auto-Ordnance Corporation sold some of the early 1928 model guns to law enforcement agencies. These Thompsons were exactly the same as the British guns described previously, except there were no British (or U.S.) military proofs or markings. It has been a common belief among many collectors, that the Savage “Commercial” guns were equipped with Colt “nickel” internal parts. A close study of these guns reveals that most of them were actually fitted with blued Savage internals. Most of these guns went to police departments where they saw rather limited use. When encountered, the police guns are generally in much better condition than the weapons that saw military service. Most of the “Commercial” model’s receivers were marked with Auto-Ordnance’s New York address. These guns did not have the cross-bolt added to the stock, as that was strictly a military upgrade.
The Savage Model of US 1928A1 (Early Production)
The letter “U.S.” began to appear on the receivers of 1928 model Thompsons after the Lend-Lease Act was passed in 1941. A provision of the act required that all weapons supplied to the allies through the program be U.S. marked. The Thompsons furnished through Lend-Lease were the same as those issued to U.S. forces.
The first U.S. 1928A1 model Thompsons accepted by the United States Ordnance Department were equipped with a Lyman adjustable rear sight and finned barrel. Virtually all military contract Thompsons destined for U.S. service were equipped with horizontal foregrips, although a few of the earlier “Limited Procurement” weapons were equipped with vertical foregrips. All M1928A1 model Thompsons were fitted with the milled front grip mount. Although a few early military Thompsons had the one-piece machined ejectors, most of the U.S. contract guns were equipped with the new three-piece riveted style. The military wood stocks and foregrips on the weapons were of a slightly lesser quality than had been seen on Colt and early Savage “Commercial” guns. Most of the early manufacture U.S. military contract Thompsons had the checkered actuator, safety and rocker levers. Subsequent production saw the elimination of the checkering on the rocker pivot levers, and eventually the safety lever, but the uncheckered actuators did not appear until later in the production run. The milled sling swivels were fitted on these guns.
A few early Savage military contract Thompsons were fitted with the rare 3rd design muzzle compensator that had the Thompson “Bullet” logo stamped on top of the device, and was not marked with the Auto-Ordnance name. Later manufacture Savage M1928A1 Models used the common “military” (4th design) Cutts compensator that featured the “Bullet” logo on the left side and the Auto-Ordnance name roll marked on the top of the unit.
Virtually all U.S. military contract M1928A1 models will have the Auto-Ordnance Bridgeport, Connecticut address roll marked on the right side of the receiver near the center. The patent numbers were marked on the right side at the rear of the receiver. Also stamped on the receivers of Savage Thompsons was the Army Inspector of Ordnance’s initials, as well as the Ordnance Department “flaming bomb” acceptance stamp. Savage guns also were marked with the initials GEG, of George E. Goll, Auto-Ordnance’s chief inspector.
The U.S. 1928A1 (2nd Variation)
The second variation of the M1928A1 Thompsons was fitted with the rudimentary fixed “L” type sight and finned barrel. The fixed “L” aperture style sight was first installed on the M1928A1s manufactured by Savage during contract number G-14 dated 24 February 1942. The contract was for 400,000 weapons. All subsequent M1928A1s were fitted with the “L” sight. The Ordnance Department felt that the M1928A1 Thompson needed a rugged military style sight with a large aperture for rapid target acquisition. Many of the aforementioned guns generally were equipped with the uncheckered safety and rocker levers, but will often have checkered actuators.
The “L” Sight
At an Ordnance Committee meeting held in December of 1941, it was suggested that a much simpler “L” type of sight replace the complicated Lyman adjustable rear sight on the Thompson. The new sight was better suited for a military application, and would help expedite production of the Thompson. The fixed “L” sight had a .125 inch aperture sighted for a 100-yard range, a second notch was cut into the top of the sight leaf for a 250-yard range. The new “L” aperture style sight was riveted to the receiver in the same manner as the early adjustable model. Lyman also manufactured many of the “L” type sights for Auto-Ordnance and were so marked. The same style of sight was used on early M1 models. The unprotected sight proved to be very easily damaged or bent and would often snag on brush and clothing. A later design provided side ears on the sight for protection of the vertical leaf. The “L” style sight began to appear on the Savage manufactured M1928A1’s at approximately the S-400,000 serial number range.
The U.S. 1928 A1 (Late Production)
The Auto-Ordnance Corporation and Savage had a difficult time keeping up with the ever-increasing demand for the Thompson. To increase production they had to either procure more machine tools and increase the work force, or simplify the parts where possible, for easier manufacture.
There were still a few amenities on the 1928 Thompson that could be eliminated in order to expedite the weapon’s production. After the complex Lyman rear sight, the next elaborate feature of the Thompson to be eliminated for the sake of production was the finned barrel. The U.S. Ordnance Department felt that the open bolt feature of the Thompson design provided enough cooling effect to prevent most premature “cook-off” of cartridges, and felt the barrel’s radial cooling fins were not needed. The smooth barrels began to appear on Savage M1928A1’s at approximately serial number S-500,000.
Late manufacture M1928A1 Thompsons were still equipped with the uncheckered, paddle style safety and rocker levers. The checkering feature was eliminated from the actuators on the late M1928A1 models. Many of the late guns were still fitted with milled style sling swivels.
Although most military 1928 Thompsons encountered today will have a reinforcing cross-bolt in the buttstock, the bolt was added after the gun left the factory. The purpose of the cross-bolt upgrade was to prevent the stocks from cracking. The cross-bolt upgrade campaign began after production of the 1928 model had ended.
The first Thompson M1928A1 models were sold to the U.S. government for “$225.00 minus 10%” which calculates to $202.50 per weapon. An additional $2.50 was added for greasing and packing costs. The price paid by the U.S. Government varied from contract to contract but steadily declined from 1941 until the end of production. The price paid by the U.S. Government for a M1928A1 had been reduced to only $70.00 when the new M1 model was introduced in July of 1942. A spare parts kit for the M1928A1 weapon was priced at $15.43.
The last 2,000 Savage U.S. M1928A1 Thompsons were manufactured in September of 1942. Thereafter Savage only manufactured the M1 and M1A1 models. Savage manufactured an estimated total of 746,932 model 1928 and M1928A1 Thompsons from April 1940, until October of 1942.
This article is condensed from the book The Military Thompson Submachine Gun, available from Moose Lake Publishing LLC. 207-683-2959 http://www.smallarmsreview.com


This article first appeared in Small Arms Review V5N5 (February 2002)
and was posted online on March 7, 2014

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By Frank Iannamico
The Savage Arms Corporation, who originally developed the M1 version of the Thompson, had continued attempts to further simplify the design by experimenting with a fixed firing pin model they designated as the M42. The prototype M42 was originally fitted with an M1 bolt with a separate firing pin, but the pin was secured in the bolt in a manner that made it a non-moveable part. The firing pin was fixed in an extended or “in battery” position. The firing pin, spring, hammer, and hammer pin were omitted. Less than 100 M42s were produced before the “fixed” separate firing pin was completely eliminated and replaced by a projection machined directly on the bolt face.
In September of 1942, Aberdeen Proving Ground was instructed to test “A modified version of the M1 submachine gun, that eliminated the firing pin, firing pin spring, the hammer and hammer pin”. The four parts were eliminated from the design by making the firing pin an integral part of the bolt. Tests at Aberdeen indicated that the M1 submachine gun equipped with a fixed firing pin functioned slightly better than the standard M1 submachine gun. It was also noted that the fixed pin design saved considerable manufacturing time and that the bolt was strengthened by elimination of the deep drilling operation necessary to accommodate the firing pin and spring. The Springfield Ordnance District was notified that manufacture of a fixed firing pin bolt for use in the M1 submachine gun was authorized. In order to distinguish between submachine guns equipped with separate firing pins and fixed firing pins, the submachine guns fitted with the fixed firing pin would be designated as Gun, Submachine, Caliber .45, Thompson M1A1. It was also noted that the bolts with and without the fixed firing pin were interchangeable. The M1A1 Thompson was formally approved at an Ordnance Committee meeting held on 29 October 1942.
In 1943, Auto-Ordnance ordered from the Savage Arms Corporation under contract G-19, 100,000 Thompson Submachine Guns M42-M1A1 type without magazines, slings or other accessories. The contract specified “Savage agrees to manufacture said guns in accordance with the United States Government specifications which are identified as AXS-725 (revision 3) dated 7 January 1943 except each of the following parts are to be incorporated in the gun. These parts shall not conform to said government specification but to the Savage, Auto-Ordnance or United States drawing number placed after the part name”. All of the parts specified had been redesigned to require less labor hours in their manufacture. The design of the M1A1 along with the redesign of many other parts for faster production had reduced the time required to manufacture an M1A1 by 10.11 hours over the earlier M1928A1 model.
Early M1A1s were equipped with many parts that were originally manufactured for use on the 1928 and M1928A1 Thompson. These parts were generally used until the supply was depleted. An example of such parts usage was; the uncheckered paddle style rocker and safety levers, the milled steel mount for the foregrip and the M1928A1 type magazine release catch. When the Thompsons were being built there was little attention paid to getting “correct” parts in the weapons. Often a mixture of new and old design parts were used in the manufacture of the M1A1 Thompsons.
The M1A1 weapons that the Savage and Auto-Ordnance factories produced were identical in appearance and specification, and all parts were completely interchangeable. Unlike the 1928 Thompsons, the manufacturer’s initials, AO or S, were not used as a serial number prefix on the M1 or M1A1. To identify who made a particular M1 or M1A1 Thompson, the manufacturer stamped their code letters on the bottom of the receiver where the front grip mount is fitted. The letters used were S, which indicated Savage manufacture, or AOC for weapons made at the Auto-Ordnance’s Bridgeport plant. As on the previous M1928A1 model, the Auto-Ordnance Corporation name and Bridgeport address is present on the receiver’s right side, regardless of who actually manufactured the weapon. The patent numbers seen marked on 1928 and M1928A1 models were not stamped on the receivers of the M1 and M1A1 weapons. Another change noted in the M1-M1A1 Thompson was the spelling of the word caliber on the receiver. The word was changed from the early spelling of CALIBRE to the U.S. recognized spelling CALIBER.
Another method of identifying the particular manufacturer of an M1 or M1A1 Thompson is by the Army Inspector of Ordnance’s initials stamped on the receiver. M1 series Thompsons produced at the Auto-Ordnance plant in Bridgeport, Connecticut would have the acceptance stamp of the AIO of the Springfield Ordnance District. Very early M1s would have the stamp WB of Colonel Waldemar Broberg on them. Later production would be marked with the GHD stamp of Colonel Guy H. Drewery, GHD. The GHD initials were often stamped near the logo on the left rear side of the receiver.
Savage manufactured M1 and M1A1s would have been stamped with the Army Inspector of Ordnance’s initials of the Rochester, NY Ordnance District. AIOs of the Rochester District were Lt. Colonel Ray L. Bowlin using stamp RLB, and Colonel Frank J. Atwood using his FJA stamp. These were usually stamped near the magazine well on the left side of the receiver. A few early M1 models were stamped with Colonel Bowlin’s RLB stamp, while the majority of the Savage M1 and M1A1’s were stamped with Colonel Atwood’s FJA mark. While the Inspector of Ordnance’s initials appear on the weapons, subordinate officers and their team of inspectors conducted the actual inspection process. All Savage M1 and M1A1 submachine gun receivers and frames were also marked with the encircled GEG acceptance stamp of Auto-Ordnance’s civilian inspector George E. Goll.
Both the M1 and M1A1 models had their serial numbers roll marked on the left rear side of the receiver and a matching number was marked on the trigger frame. The trigger frame number is usually located on the bottom of the trigger guard. Like the 1928 and M1928A1 guns, the M1-M1A1 receivers and frame were originally matched and fitted at the factory, but purely for cosmetic reasons. A mismatched frame-receiver is fairly common and has no bearing on the proper functioning of the weapon. There have been many M1A1 trigger frames documented that did not have serial numbers stamped on them. The practice of placing a duplicate receiver serial number on trigger frames ceased in January of 1943 as per specification AXS-725. However, the practice of selective fitting of frames to receivers still was performed at the factories.
There are some interesting differences in the markings on M1 and M1A1 Thompsons that vary between the weapons manufactured by Savage Arms and those made by Auto-Ordnance, Bridgeport. On trigger frames of Savage manufacture, the words FULL AUTO are marked on two lines, while on Auto-Ordnance frames the words FULL AUTO are on one line. Some of the M1A1 Thompsons were marked US PROPERTY on the receiver just behind the rear sight. On Savage produced weapons the letters US are stamped on one line, and the word PROPERTY is on a second line underneath it. The US Property stamp was marked to be read from the rear of the receiver. On Thompsons of Auto-Ordnance, Bridgeport manufacture the US PROPERTY was roll marked on one line and was marked to be readable from the front of the weapon. Not all M1A1 Thompson guns had the U.S. Property stamp on them, the reason for this is not known for certain, but one possible explanation could be that those stamped with U.S. Property markings were destined for the Lend-Lease Program. One of the requirements of the Lend-Lease program was that the weapons provided through the program be U.S. marked. There were no early M1 models documented or examined by the author that were U.S. Property marked.
One other minor difference between the early M1 and later M1A1 Thompson’s is the configuration of the receiver. On M1’s the back end of the receiver was squared off and has somewhat sharp edges, while the M1A1’s studied had rounded edges at the rear of their receivers.
On many M1A1 Thompson guns manufactured at the Auto-Ordnance, Bridgeport plant the A1 designation appears to have been added by hand stamping. This has led many collectors to believe that these were originally M1 weapons, which is true in part. The Auto-Ordnance, Bridgeport facility had a difficult time when changing over from M1928A1 to M1 production, resulting in a several month delay in the start of their M1 production run. This delay was followed by another, when the weapons were rejected by the Springfield Ordnance District inspectors, because their full-auto cyclic rate exceeded the specifications. By the time the problems were resolved, and the Bridgeport plant M1 guns were finally being accepted by Ordnance, the M1 had been superseded as Standard by the M1A1 model. Most all of the receivers on hand at Bridgeport had already been roll marked M1, but were upgraded to the new M1A1 configuration by replacing the bolts. This necessitated the hand stamped addition of the A1 suffix on these weapons at the factory.
In January of 1943 the Ordnance Department announced to the Auto-Ordnance Corporation that the Thompson was going to be replaced by the newly developed U.S. M3 submachine gun. After the Ordnance Department’s official adoption of the M3 submachine gun, Thompson production was scheduled to be concluded in July of 1943. Plans were made to begin tapering off production of the weapon. In April 1943 62,948 M1A1 guns were built, this was reduced to 55,000 in May and 51,667 in June. This left only 5,000 guns remaining to be manufactured in July. Authority was then received from the Ordnance Department in June to procure an additional 60,000 weapons by the end of August. Before the end of August more orders for the Thompson were received from Washington. A total of approximately 119,091 additional Thompson M1A1 models were to be manufactured, providing continuance of production through December of 1943. At the end of December there were enough parts remaining to assemble approximately 4,500 additional guns. In January of 1944 authorization was granted to complete the remaining guns by 15 February 1944. Production briefly resumed in February completing a total of 4,091 additional guns. On February 15, 1944 the very last M1A1 Thompson Submachine Gun was accepted by the government against contract W-478-ORD-1949.
There were several manufacturing problems encountered with the new M3 that had caused Thompson production to be extended for several months until the M3 production difficulties could be solved. By the time of the last procurement of the M1A1 Thompson, the price charged to the United States government had been reduced down to $42.94 per weapon.
M1 and M1A1 Thompsons that were manufactured by Savage were originally assembled with parts produced by the Savage or Stevens companies. M1 and M1A1’s manufactured at Auto-Ordnance’s Bridgeport plant were assembled with parts supplied by a variety of contractors.
The Savage Arms Corporation manufactured an estimated total of 464,800 M1 and M1A1 model Thompsons, while the Auto-Ordnance Bridgeport plant turned out an estimated 249,555 M1 and M1A1s.
This article was partially excerpted from the new book “American Thunder, the Military Thompson Submachine Guns”. The book is now available from Chipotle Publishing 702-565-0746


This article first appeared in Small Arms Review V6N2 (November 2002)
and was posted online on December 20, 2013

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Thompson M1a1 Serial Number Database Guitar

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