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Umarex Legends M1A1

The original SMG and history

First issued in 1943, the M1 uses a simple blowback operation, with the charging handle moved to the side. The flip-up adjustable Lyman rear sight was replaced with a fixed L sight. Late M1s had triangular guard wings added to the rear L sight, which were standardised on the M1A1. The slots adjoining the magazine well allowing the use of a drum magazine were removed. A new magazine catch with the provision for retaining drum magazines removed, was produced, but most M1s and later M1A1s retained the original.

The less expensive and more-easily manufactured “stick” magazines were used exclusively in the M1, with a new 30-round version joining the familiar 20-round type. The Cutts compensator, barrel cooling fins and Blish lock were omitted while the butt-stock was permanently affixed. Late production M1 stocks were fitted with reinforcing bolts and washers to prevent splitting of the stock where it attached to the receiver. The British had used improvised bolts or wood screws to reinforce M1928 stocks. The M1 reinforcing bolt and washer were carried over to the M1A1 and retrofitted to many of the M1928A1s in U.S. and British service.

Late M1s also had simplified fire control switches, also carried over to the M1A1. Certain M1s had issues with high rate of fire climbing up to ~800 RPM. The exact cause remains unknown, but was resolved with the transition to the M1A1.

The Thompson M1A1 SMG

The M1A1, standardised in October 1942 as the United States Submachine Gun, Cal. .45, M1A1, could be produced in half the time of the earlier M1928A1, and at a much lower cost. The main difference between the M1 and M1A1 was the bolt. The M1 bolt had a floating firing pin and hammer, the bolt of the M1A1 had the firing pin machined to the face of the bolt, eliminating unnecessary parts.

The reinforced stock and protective sight wings were now standard. The 30-round magazine became more common. In 1939, Thompsons cost the government $209 apiece. By the spring of 1942, cost-reduction design changes had brought this down to $70. In February 1944, the M1A1 reached a low price of $45 each, including accessories and spare parts, although the difference in price between the M1 and M1A1 was only $0.06. By the end of the war, the M1A1 was replaced with the even lower-cost M3 (commonly called the “Grease Gun”).

TV and film

The Thompson M1A1 is a major feature in many films and tv shows, my choices include Kelly’s Heroes, Saving Private Ryan and Diamonds Are Forever, with tv shows including Foyle’s War, Dad’s Army featured the earlier M1928A1 with round magazine.


  • Calibre: .45 ACP
  • Capacity: 30 rounds
  • Weight: 4.7kg
  • Length: 810mm

The CO2 replica

The Umarex Legends M1A1 Thompson SMG is another wonderful replica. It is stunningly accurate in appearance with the worn look given to the metal by the “Legends” team.

It features faux wood grips but the effect is pretty good and takes a second look to tell, however they are much lighter than real wood which shows in the weight of the replica. I ‘fixed’ this weight issue by loading all the plastic parts with Plasticine modelling clay – this not only brings the weight up nicely to that of the real SMG, it also removes the hollow plastic sound.

The Legends M1A1 right side

The trigger is very usable and will fire as fast as you can pull it, the magazine release catch is in the right place and works well. Naturally the “auto/single” mode switch only goes one way for the UK. There is very little white lettering which is good. The bolt is full blowback and gives a good feel when fired.

The Legends M1A1 left side

The sling and bag are not included, I ordered these from an on-line replica military kit supplier and they boost realism nicely I think.

The magazine holds two CO2’s

The magazine holds two 12g CO2 cartridges loaded back to back. It will also run on one new and one used cartridge if less play time is wanted. Tip – clean and lubricate the threads and seal of the CO2 chamber bung with something like Crosman “PellGun” oil – the metal is fairly weak and the threads strip easily, do not use silicone oil or grease here as it is useless for metal to metal contact and can cause it to gall.

BB loading slot

BB loading is easy, the plunger is large and easy to grip, a speed-loader works well too.

In use, the M1A1 Thompson is great, it’s accurate, powerful and with the blowback style bolt it’s engaging to shoot with good feedback. This iconic replica is a must for the collector I think.


  • Calibre: 4.5mm BB
  • Capacity: 30 rounds
  • Weight: 3.6kg unweighted or 4.6kg with stocks/grips weighted.
  • Length: 805mm
  • CO2 Usage: Around 150 shots with two cartridges loaded.