Exclusive First Review Of The M1A1 Thompson BB Gun


Testers: Doug Wall, Stephen Archer

Caliber: .177 BB

Model Number: 2251820

Test Date: Nov 30, 2019

Serial Numbers: DE000009

Source of Supply: Umarex USA

Condition: New

We Like

Very faithful replica
Great shot count
Excellent accuracy

We Don't Like

No BB follower hold down
Non-adjustable sights
Nothing else!


  • Value for Money
  • Comparison to Makers Claims:
  • Consistency
  • Appearance and Finish
  • Buying and Owning
  • Realism, Look & Feel
  • Realism, Trigger Action
  • Accuracy & Point of Aim
  • Shot Count
  • Muzzle Velocity



The M1A1 Thompson BB gun is simply an amazing airgun. It combines extreme realism of appearance and operation with a very high shot count. That 96% HAM score equals that of the best we’ve ever awarded. It’s an obvious HAM Gold Award winner!

Buy one. And while you’re at it, buy a TON of BBs and CO2 cartridges. Get some spare magazines too.

You’ll have a huge amount of fun shooting this full auto reproduction of the iconic Tommy gun. We did 🙂


The M1A1 Thompson BB gun is currently listed at a Street Price of $224.95. This is in advance of the first deliveries hitting dealers’ shelves, but HAM anticipates that demand will be huge and this price is unlikely to fall in the forseeable future.

At this price, it’s at the top end of BB-firing replica firearms pricing. But it’s so good that the HAM Team feels it’s great value, particularly given the performance of the sample tested by HAM!

And – as HAM Tester Doug Wall wrote in his test notes – “It sure beats the $16-25K being asked for a real one!”

M1A1 Thompson BB Gun

HAM Test Rating96%
Value For MoneyGreat realism, accurate, huge shot count.
Firearm it CopiesThompson M1A1
Best BB TestedASG Blaster BBs
Street Price at Time of Test$224.95.
Ammo Type.177 BBs.
Power Source2 x 12 Gram CO2 cartridge.
Useful Shots per FillUp to 218.
Legends M1A1 .177 Full Auto Blowback CO2 BB Gun 0.177
Umarex Legends M1A1 BB Gun



First off, these comments need to be understood in the context that none of the HAM Team have actually fired a Thompson M1A1 firearm. That probably applies to about 99.99% of  future BB gun owners, too.

But our first comment about the realism of this M1A1 Thompson BB gun is “WOW!

M1A1 Thompson BB Gun

It certainly looks exactly like the real thing. The size and proportions are right-on, too.

The obligatory BB gun “warning text” has been banished to the underside of the trigger guard. Metal parts are well finished in a powder coat black that is a very fair representation of the military firearms finish.

Safety and fire selector levers are fully-functional, as is the bolt and magazine release. And then there’s the realism of the “woodwork”. Yes, the forend, pistol grip and buttstock are printed synthetic material but they look amazingly realistic. Until you touch them no-one would believe that they are not made of real “tree wood”!

The only downside the HAM team can see is that the all-up weight of the M1A1 Thompson BB gun is rather lighter than that of the original. The firearm weighs about 10 Lbs. The BB gun comes-in at 7LBs 12 Oz. That difference is almost certainly due to the different “woodwork”.

So the M1A1 Thompson BB gun is a couple of Lbs lighter than the original. But it still feels solid and weighty in the hand.

Wood furniture kits have been available for airsoft versions of the M1A1 and as military surplus for the firearm, the cost being in the $50 -100 range. We’re guessing that such parts may well fit this BB gun.

If an owner of the M1A1 Thompson BB gun really wanted ultimate realism, that could be the way to go – if such kits are available at the current time. But once you’ve seen the quality of the synthetic “woodwork” you may well decide it’s not necessary to make the upgrade.

The only downside to the synthetic stock is that the sling swivels clatter against them in use. This noise is stopped when you install a sling, however.



The accuracy of the M1A1 Thompson BB gun tested by HAM was very good. So good, in fact, that HAM tester Doug Wall fired all his tests at 10 Yards.

Best accuracy was obtained with ASG Blaster BBs. These gave a 10-shot group of 1-inch CTC at 10 Yards, which is really very good for any BB gun. The only BB gun tested by HAM to show better accuracy to date was also an Umarex Legends model – the Cowboy Rifle.

Unfortunately the gun tested by HAM had a strong tendency to shoot low and a little left. Doug therefore aimed off, as you can see from the test targets below. As he noted in his test notes: “It really needs an adjustable rear sight. Accuracy is good enough to make use of it.”



UmarexUSA makes some claims for the M1A1 Thompson BB gun. These are as follows and we’ll check them out:

– A realistic reproduction of the firearm. Check!

– Realistic full auto, open bolt blowback action. Check, check. It’s so realistic that the muzzle even climbs a little on extended full-auto firing!

– Up to 435 FPS Muzzle Velocity. Check. The M1A1 Thompson BB gun tested by HAM actually peaked at 402 FPS with Crosman Copperhead BBs at 62 Degrees F.

We know that all CO2-powered airguns shoot faster at higher temperatures. (So long as they’re fired at relatively slow rates, that is). That increase is around 2 FPS per degree F.

This means that the HAM test result of 402 FPS at 62 degrees would match the manufacturer’s claim at 78 degrees ambient temperature. It also means that it would exceed the claim at higher temperatures, peaking at about 460 FPS at around 90 Degrees F. Above that temperature, valve lock would likely cut-in causing FPS to drop – this is a characteristic common to all CO2-powered airguns, not just our Tommy gun.


The M1A1 Thompson BB gun tested by HAM demonstrated very good consistency.

Standard Deviation – the variation in FPS in a string was extremely good at an average of just 5.11 FPS across the HAM standard range of test BBs. That’s a figure that would be very acceptable for any PCP air rifle costing $1,000!

Actual Muzzle Velocity was also consistent in the 390 – 400 FPS range across the different types and weights of BBs tested.

The point of impact on target was consistently low and generally a little left of center with these BBs also.

Trigger pull weight averaged 7 Lbs 6 Oz. It varied by only -4 to + 6 Ounces around that average. Again, very good performance.



Both trigger and action are highly realistic on the M1A1 Thompson BB gun. The gun is cocked by pulling back on the charging handle, letting it fly forward. Just like the firearm.

The safety and fire selector levers also operate just like the “real thing”. As does the magazine release. That’s a drop free magazine also, by the way.

The blowback action is very realistic, giving a real feeling of recoil – particularly on a fresh pair of CO2 cartridges. And – as mentioned above – there’s even muzzle climb when extended strings are fired on full auto. The gun “hammers” well in full auto, yet can be fired accurately when set to single shot mode.

The bolt locks back when the mag is empty, too. This gun is not field-strippable, however that’s a small price to pay for the overall realism.

Trigger pull weight of the M1A1 Thompson BB gun tested by HAM is about a Pound lighter than the specs for the firearm. But “government guns” made during WWII could well have shown some variation against that spec. And we can’t easily tell the difference between 7.5 Lbs-ish and 8.5 Lbs. They’re both pretty heavy…

The trigger has a two-stage action with a distinct “wall” for the second stage. And, of course, this is a sub-machinegun trigger, not that for a target rifle! The HAM Team had no issues with this trigger for its intended use.



Here, the M1A1 Thompson BB gun tested by HAM really excelled! Doug found that no less than 218 were obtained from a full charge of two, 12 Gram CO2 cartridges.

This is an outstanding number! The HAM Team’s expectations were for about 150 shots, similar to the Legends MP40 we tested.

Yes, the Muzzle Velocity of the M1A1 Thompson BB gun tested by HAM was around 30 FPS slower than the MP40, but the extended shot count was still outstanding for a full blowback action.

That compares to the 110 shots of the non-blowback Legends Cowboy Rifle tested by HAM. However the Cowboy Rifle did give a significantly higher Muzzle Velocity in the 575 FPS range. As always, you just can’t have high shot count, high FPS and strong blowback all at the same time from any CO2-powered airgun!



As always, HAM testing was undertaken in relatively cool conditions. This time it was 62 degrees F on the range.

This is rather cool for CO2-powered airguns, however, the M1A1 Thompson BB gun tested by HAM produced a good performance in spite of the temperature. The maximum average Muzzle Velocity for a 10-shot string was 402 FPS. This was achieved with Crosman Copperhead BBs.

BBsAverage Muzzle VelocityAverage Muzzle EnergyAccuracy
Crosman Copperhead 5.13 Grain402 FPS1.84 Ft/LbsPoor.
Umarex Steel 5.29 Grain390 FPS1.78 Ft/LbsExcellent.
ASG Blaster 5.32 Grain387 FPS1.78 Ft/LbsExcellent. Best Tested.
Hornady Black Diamond 5.36 Grain394 FPS1.85 Ft/LbsExcellent.
Daisy Avanti 5.44 Grain389 FPS1.83 Ft/LbsVery Good.

M1A1 Thompson BB Gun



The M1A1 Thompson BB gun looks superb. There are no machining marks on the metal and only a very fine molding seam on the synthetic stock. All functional controls are correctly positioned and work just as on the firearm.

Again, the synthetic “wood” is superbly represented.



The M1A1 Thompson BB gun is covered by the regular, brief, Legends 90-day warranty. However, as the valve is located in the detachable magazine (additional mags are available at $49.95), the main cause of possible problems with any CO2-powered gun can simply be resolved through swapping magazines.

Although not shipping yet, the M1A1 Thompson BB gun will be available from all the usual Umarex USA dealers – both physical and online.

It’s true that HAM did not receive final packaging and documentation with this pre-production sample. However, we know that the standard of Legends packaging and user guides is very high and fully expect that to be the case with this product too.

Umarex will be providing a BB speed loader with this gun. But unfortunately there is no BB follower hold-down catch. This is a failing common to the MP40 and some – but not all – other Umarex BB guns.

It means that you need to constantly pull down the BB follower against spring pressure to load the BBs. This requires a very strong thumb nail!!!

HAM Tester Doug Wall became so frustrated with this issue that he made an ingenious BB follower hold open tool for himself! You can see it in the photographs below.

Doug’s tool is elegant in its simplicity and works perfectly. It bears against the base of the magazine and holds the BB follower down so that BBs can be poured in.

Umarex should mass-produce this tool and include it with the M1A1, MP40 and others. And Doug should receive royalties for his superb, innovative design!!!

A separate Allen (hex) wrench is required for installing CO2 cartridges. Of course, one is supplied with the M1A1 Thompson BB gun. But if you loose it, you may like to know that the size is 6 mm metric.

Finally, you definitely will want to buy several additional magazines for the M1A1 Thompson BB gun! Given the huge fun factor, having multiple magazines pre-loaded with CO2s and BBs is the best way to ensure a long, enjoyable shooting session with this model.


SAFETY FIRST. As with all BB-firing airguns, it’s necessary to wear shooting glasses when firing this airgun. Also do not shoot at hard surfaces or water. BBs tend to bounce off these surfaces and may hit you, or something other than what you intended. If in doubt, don’t pull the trigger! Due to the realistic appearance of this product, handle it as you would a firearm. Do not display it in public or in any place where it could be mistaken for a cartridge firearm.


M1A1 Thompson BB Gun

M1A1 Thompson BB Gun

M1A1 Thompson BB Gun

M1A1 Thompson BB Gun

M1A1 Thompson BB Gun

Legends M1A1 .177 Full Auto Blowback CO2 BB Gun 0.177
Umarex Legends M1A1 BB Gun

This entire article including scoring, test targets etc is Copyright Hard Air Magazine and may NOT in part or in whole be reproduced in any electronic or printed medium without prior permission from the publisher.