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
The Thompson Submachine Gun was first used in combat when they were carried by U.S.
Marines in Nicaragua during the Banana Wars. It wasn’t until World War II that the Thompson
Submachine Gun received the nickname Tommy Gun, after it was adopted by the British before the
United States officially entered the war as a combatant on the side of the Allies.
Depending on the model, the Thompson Submachine Gun fired a .45 ACP caliber pistol
cartridge from a detachable 50 or 100 round drum magazine, or a 20 or 30 round metal box “stick
magazine” and had a rate of fire of 600 to 800 rounds per minute. U.S. Navy models were
manufactured to fire at a slower rate to conserve ammunition and make the weapon more controllable
under full automatic fire. The average weight of an unloaded Thompson Submachine Gun was just
under 11 pounds. When loaded with a 30 round magazine of 230 grain .45 ACP ammunition the
Thompson weighed closer to 13 pounds.
Despite the fact that the Thompson was heavy when loaded to the brim with .45 ACP
ammunition, most of the troops who carried one liked having a “Tommy Gun” in their hands 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 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 a handy 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 spray a cave, or an enemy stronghold, with a large number of bullets,
to insure that there was no further threat to advancing or passing Allied military personnel. The
Thompson was also the ideal weapon for armored vehicle crews to carry, in case they were forced to
dismount and fight as infantry.
During World War II, U.S. and Allied forces used Thompson Submachine Guns that were
modified to reduce the cost of production and make the weapon more user friendly. One of these
modifications involved replacing the more complicated original rear sight with a rudimentary but
effective sight, that was less time consuming and less expensive to manufacture.
From a mechanical standpoint the major changes between the original Thompson and later
wartime 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 straight blow back design to facilitate firing the weapon. Wartime M1
and M1A1 Thompson Submachine Guns were also intended to be used with 20 and 30 round metal box
(stick) magazines. Drum magazines and 20 round stick magazines were issued early in the war and
were eventually replaced by 30 round “stick” magazines.
Spare 50 round drum magazines for the Thompson were carried in a well made cotton canvass
pouch. A canvass ammunition pouch that was attached to an adjustable canvass pistol belt held five
twenty round magazines. Thirty round magazines were carried in a pouch that was designed to hold
three magazines. Twenty and thirty round magazines were also carried in other canvass bags and were
carried tucked into belts, or in field jacket pockets. Some combat veterans who carried a Thompson
sometimes carried one magazine loaded in their weapon and one or two stuffed in their back pocket.
This was done to lighten their load and because an experienced soldier could do a great deal of damage
with 60 or 90 rounds of .45 ACP ammunition, especially in a submachine gun that could be fired in
short bursts, or in the single shot mode. This was accurately portrayed on the TV Show Combat, when
actor Vic Morrow playing Sergeant Chip Saunders, usually carried a minimal number of spare 30 round
magazines inside his field jacket pocket and not in an ammunition pouch on his pistol 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. He did so when it was
far too hot and humid in the jungle, to be weighed down with an exceptionally heavy combat load.
The U.S. Navy was the first branch of the service to notice the merits of the submachine gun
and placed an order for Model 1928 Thompson sub machine guns. The U.S. Army soon followed and
officially adopted the M1928A1 in 1938 as a standard issue Submachine Gun .45 Caliber. The M1 and
M1A1 appeared later in the war.
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, because it had been
used by armed professionals and gangsters for several decades. It should also be noted that since all
firearms required the proper cleaning in the field, those who liked carrying a Thompson did not mind
the maintenance chores that were required to keep their submachine gun operational. 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 Thompson when it came time to pull the trigger in combat. In fact,
the weight of the Thompson kept the recoil to a minimum and made it possible to accurately and more
easily fire this weapon.
For various reasons a Thompson that provided reliable service was often treasured by the men
who were lucky enough to carry one, especially when submachine guns were in short supply. 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 1.3 million M1928A1, M1 and M1A1 Thompson Submachine Guns were supplied to
Allied forces during World War II. Thompson Submachine Guns went on to serve in The Korean War,
with specimens also serving in The Vietnam War.
Military Small Arms of the 20th Century by Ian V. Hogg and John Weeks.
U.S. Infantry Weapons of World War II By Bruce N. Canfield.
Infantry Weapons of World War II By Jan Suermindt.
Guadalcanal Marine By Kerry L. Lang.
Weapons of the Navy SEALs by Kevin Dockery.
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.