THE THOMPSON SUBMACHINE GUN MODEL 1921, SUBMACHINE
GUN CALIBER .45 MODEL 1928, 1928A1, M1 THOMPSON AND M1A1
AKA THE THOMPSON SUBMACHINE GUN
BY: NICK JACOBELLIS
U.S. Marines were the first combat troops to carry Model 1921 Thompson Submachine Guns
during “The Banana Wars.” These “police actions” and occupation force assignments took place in
various countries/locations in Central America and the Caribbean from 1898 until 1934. The U.S. Navy
was the first branch of the U.S. armed services to place an order for what would become the first batch
of government stamped/issued M1928 Thompson Submachine Guns. The U.S. Army officially adopted
the Thompson in 1938 as the United States Submachine Gun, Cal. 45 M1928A1.
It was during World War II that the Thompson Submachine Gun received the nickname
“Tommy Gun.” This occurred when the Thompson was adopted by the British, before the United
States officially entered World War II as a combatant. The name Tommy Gun was patented by the Auto
Depending on the model, Thompson Submachine Guns had a rate of fire of 600 to 800 rounds
per minute. U.S. Navy Models were manufactured to fire at the slower rate of fire to conserve
ammunition and make the weapon more controllable when fired. The weight of an unloaded
Thompson Submachine Gun varied somewhat with the different models and ranged from 10 pounds to
just under 11 pounds. A basic combat load of five 20 round metal magazines weighed 2 pounds
without the weight of the 100 rounds of .45 ACP caliber ammunition. The basic combat load of
three unloaded metal 30 round metal box magazines weighed 1.5 pounds. An unloaded 50 round metal
drum magazine weighed 2.5 pounds.
Despite the fact that the Thompson was heavy when fully loaded with .45 ACP ammunition,
most of the troops who carried one liked being armed with a “Tommy Gun” when they went into
combat. Before an ample number of Thompson Submachine Guns were in circulation, Allied armies
made the bulk of these weapons available to specialized personnel such as, commandos,
paratroopers and tank crews, before they were issued in larger numbers to infantry divisions and other
front line personnel.
Even though the Thompson was widely used in all theaters of operation, submachine guns had
their limitations and were not the ideal weapon to have, if you were fighting in terrain where it was
necessary to engage targets at longer distances. Being a handgun cartridge, .45 ACP bullets were
understandably less effective in certain situations than 30.06 or .303 rifle ammunition. However,
the Thompson was very effective when fighting in an urban setting, in the jungle, or in forested terrain.
Despite being on the heavy side, the Thompson proved to be one of the most rugged, reliable
and powerful submachine guns used during World War II. Thompsons were especially handy when
used to spray tree tops to “recon by fire” when trying to kill well concealed enemy snipers. The
Thompson Submachine Gun also proved to be an effective weapon to be armed with, when enemy
troops attacked a fixed U.S. or Allied position, especially at night. Submachine guns were also favored
by troops, when it was necessary to engage enemy combatants in confined spaces, to include, in a cave,
inside a building, or in a bunker/pill box. The Thompson was also an ideal weapon for armored vehicle
crews to possess when they were forced to dismount and fight as infantry. Being armed with a
Thompson also provided armored vehicle crews with the means to protect their encampments, when
they stopped in forward areas, especially at night.
As World War II progressed, U.S. and Allied forces used Thompson Submachine Guns that
were redesigned to use different or fewer parts, that reduced the cost of production and expedited the
manufacturing process. These models were designated the M1 and M1A1. One of these modifications
involved replacing the more complicated original rear sight with a rudimentary but effective L shape
sight, that was less time consuming and less expensive to manufacture. Other modifications between
the M1928A1 Thompson and the M1 and M1A1 models involved the use of a fixed stock that could
not be removed by the operator, the removal of the Cutts Compensator on the end of the barrel to
reduce muzzle climb under firing conditions, the relocation of the cocking handle from the top of the
receiver to the right side of the receiver and the adoption of a horizontal for-end/forward grip, instead
of the angled vertical forward grip, that was featured on earlier models.
Both the M1 and M1A1 variants also eliminated the need to use the Blish Locking Device and
transitioned to a straight blow back design for an operating mechanism. Making this change reduced
the number of parts and the time that it took to manufacture the M1 and M1A1 models. The production
of the M1A1 Model was further modified, by utilizing a bolt with a fixed striker that acted as a firing
pin. This particular modification replaced the use of an additional separate part known as the firing pin.
World War II era Thompson Submachine Guns also had a Parkerized Finish to protect these firearms
Even when the M1928A1 Thompson was modified/redesigned to cut production cost and
production time, the M1 and M1A1 variants remained a rugged and reliable firearm. It should also be
noted, that a number of M1928A1, M1 and M1A1 (United States Submachine Gun, Cal. 45) were
arsenal upgraded, modified, repaired and refurbished before being put back into service.
While all Thompson Submachine Guns could be reliably operated using a 20 and or a 30 round
metal box (stick) magazine, only the earlier wartime models known as the M1928A1 Thompson would
accept a 50 round Drum magazine. In fact, during the early stages of WWII, the M1928A1 models
were generally used with a Drum magazine and or 20 round box/stick magazines. The 30 round
box/stick magazine eventually became the standard loading device for wartime issued Thompsons.
The inherent reliability of the Thompson metal box or stick magazines rested in their spring loaded
double stack design.
A spare 50 round drum magazine for the M1928M1 Thompson was carried in a well made
cotton canvass pouch that was fitted with a shoulder strap. A canvass ammunition pouch that was
attached to an adjustable canvass pistol belt held five 20 round magazines. The 30 round magazines
were carried in a pouch that was designed to hold three magazines. Twenty and thirty round Thompson
magazines were also carried in other canvass bags and were carried tucked into belts.
In certain situations, WWII combat veterans who carried a Thompson would carry one
magazine loaded in their weapon and one or two stuffed in pocket on their uniform clothing. This was
done to lighten their basic “combat” load and because an experienced soldier could do a great deal of
damage with 60 to 90 rounds of .45 ACP caliber ammunition. An example of this was accurately
portrayed on the 1960s era hit TV series Combat, when actor Vic Morrow, who played Sergeant Chip
Saunders, usually carried a minimal number of spare 30 round magazines inside his field jacket pocket.
Only in some of the earlier episodes, did the Sgt. Saunders character carry spare magazines for his
M1928A1 Thompson, in a canvass magazine pouch on his belt. This was also verified to me by a
WWII combat veteran, who served in the Pacific and often carried a spare magazine for his Thompson
in his back pocket, when he went on certain patrols. This particular GI did so, when it was far too hot
and humid in the jungle, to be weighed down with an exceptionally heavy combat load.
In addition to its graceful lines and rugged appearance, the Thompson Submachine Gun had a
tremendous reputation that was cloaked in a great deal of history and nostalgia. This was the case,
because Thompson Submachine Guns were used by armed professionals and gangsters for many years,
before the outbreak of World War II. Even though a Thompson Submachine Gun and a decent supply
of loaded magazines was heavy to carry, it was well worth the effort to be armed with a “Tommy Gun,”
when it came time to pull the trigger in combat. In fact, the weight of the Thompson helped to reduce
felt recoil and made it possible to accurately and more easily fire this weapon.
Even when the lighter M3 Grease Gun became available, many American soldiers and marines
preferred the Thompson, over the submachine gun that looked more like a mechanics tool, than a finely
crafted firearm. Over 1.5 million M1928A1, M1 and M1A1 Thompson Submachine Guns were
supplied to Allied forces during World War II. Of this number, some 560,000 M1928A1s were
manufactured, which is more than any other model. Thompson Submachine Guns went on to serve in
The Korean War, with specimens also serving in The Vietnam War.
Nick Jacobellis is a Medically Retired U.S. Customs Agent and a former NY police officer who was physically disabled in the line of duty while working undercover as a federal agent. To date, the author has published over 205 magazine articles and nine action-packed nonfiction, historical fiction, and fiction books: Controlled Delivery Books One and Two, The Frontline Fugitives Books I, II, III, and IV, Buck Banderas U.S. Marshal Books One and Two and A Special Kind of Hero. These books have received 5 Star reviews and are available on Amazon.com (US), and (UK). He was born and raised in Flatbush section of Brooklyn NY and has an BS Degree in Police Science from John Jay College of Criminal Justice.
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About the author: Nick Jacobellis is a Medically Retired U.S. Customs Agent and a former NY police officer who was physically disabled in the line of duty while working undercover as a federal agent. To date, the author has published over 205 magazine articles and nine action-packed nonfiction, historical fiction, and fiction books: Controlled Delivery Books One and Two, The Frontline Fugitives Books I, II, III, and IV, Buck Banderas U.S. Marshal Books One and Two and A Special Kind of Hero. These books have received 5 Star reviews and are available on Amazon.com (US), and (UK). He was born and raised in Flatbush section of Brooklyn NY and has an BS Degree in Police Science from John Jay College of Criminal Justice.