Right, but the M1 and M1A1 were not the only models to see service in theater. Dutch is correct: there were Drum mags on WWII battlefields. The M1928 had been adopted into service previously and it's not uncommon to see pictures and video of it fitted with a drum, especially in the pacific.
Guadalcanal, 1942.
July 1943
But as far as accuracy on the M1 and M1A1 models, you're absolutely correct. No drum mags there. Certainly as far as Vietnam goes, the Thompson SMGs that found their way into theater were--the vast, vast majority of the time--surplus M1 and M1A1s leftover from WWII. We sent a good few of them to the ARVN.
Model 1928
The Model 1928 was the first type widely used by military forces, with the U.S. Navy and U.S. Marine Corps as major buyers through the 1930s. The original Model 1928s were Model 1921s with weight added to the actuator, which slowed down the cyclic rate of fire, a U.S. Navy requirement. The Navy Model 1928 has several names by collectors today they are; the 'Colt Overstamp', 'The 1921 Overstamp', '28 Navy', or just '28N'. The "overstamp" term refers to the '1' in '1921' being stamped over with an '8'. The 1928 Thompson would be the last small arm adopted by the U.S. Army that used a year designation in the official nomenclature. With the start of World War II, major contracts from several countries saved the manufacturer from bankruptcy.
M1928A1 at Fort Knox, Kentucky, June 1942
The M1928A1 variant entered mass production before the attack on Pearl Harbor, as on-hand stocks ran out. Changes included a horizontal forend, in place of the distinctive vertical foregrip ("pistol grip"), and a provision for a military sling. Despite new U.S. contracts for Lend-Lease shipments abroad to China, France, and the United Kingdom, as well as the needs of American armed forces, only two factories supplied M1928A1 Thompsons during the early years of World War II. Though it could use both the 50-round drum and the 20- or 30-round box magazines, active service showed the drums were more prone to jamming, rattled when moving, and were too heavy and bulky on long patrols. 562,511 were made. Wartime production variants had a fixed rear sight without the triangular sight guard wings and a non-ribbed barrel both like that found on the M1/M1A1.
In addition, the Soviet Union received M1928A1s, included as standard equipment with the M3 light tanks obtained through Lend-Lease. The weapons were never issued to the Red Army, however, because of a lack of .45 ACP ammunition on the Eastern Front, and were simply put in storage. As of September 2006, limited numbers of these weapons have been re-imported from Russia to the United States as disassembled "spare parts kits", the entire weapon less the receiver (as required by Federal law).
In 1943 the M1 and the M1A1 were both adopted and the 1928's were returned which in turn limited the numbers drastically.
Thats very true but we use M1A1 in BC2 Vietnam.
