Testing the Tommygun—Thompson M1A1BB gun: Part Two

M1A1 BB submachinegun.

Part 1

This report covers:

• Charging with CO2
• Loading
• Select-fire
• Daisy BBs
• Discharge sound
• Crosman Black Widows
• Trigger
• The bolt handle moves
• H&N round lead balls
• Full auto
• Shot count
• Summary

Today we fire the Thompson M1A1BB gun for the first time. This will be a velocity test, plus we will check out some other things that we have wondered about.

Charging with CO2

This submachine gun takes two 12-gram CO2 cartridges. They fit in the stick magazine, with the first one going in down and the second up. Down and up refer to the piercing flat on the cartridge tip. And you put Crosman Pellgunoil or some other sealing oil on the tips of both cartridges to keep the interior seals fresh.

Loading

Thirty BBs also go in the magazine. And it is super-easy to load! Lay it flat with the loading channel on top and lock the follower back. Then drop the BBs into the grooved channel above the loading port. I find that placing something under the rear of the mag to create a slight slope speeds the process. Let the BBs roll in. 

This is how to load the magazine easily.

And that’s the magazine loaded with H&N copper-plated round balls.

Select-fire

I covered this in Part 1. The fact that this BB gun has select fire makes it easy to chronograph. I will note that the velocity does decrease as shots are fired and the owner’s manual even mentions this.

Daisy BBs

First to be tried were Daisy BBs, Ten averaged 457 f.p.s. The velocity spread went from 449 to 462 f.p.s., a spread of 13 f.p.s.

Discharge sound

The Thompson discharged at a level of 96 decibels. That’s reasonably quiet.

Crosman Black Widows

Next up were ten Crosman Black Widows. They averaged 456 f.p.s. The low was 447 and the high was 465—a difference of 18 f.p.s.

Trigger

I will say this Thompson has a two-stage trigger. There is definitely some take-up before the trigger stops. I won’t call stage two crisp, but you do know it’s there.

The bolt handle moves

One question we had in Part 1 was does the bolt handle move when the gun fires and the answer is yes. I don’t think it will be dangerous to anyone, either right or left-handed shooters, because the design of the gun keeps your body parts well away from that handle. You’d have to work to get hurt by it.

H&N round lead balls

I’m out of H&N Smart Shot BBs, but I think the H&N copper-plated lead balls I used are the same thing by another name. The Thompson stick magazine makes them a possible choice.

Ten averaged 391 f.p.s. The low was 373 and the high was 404 f.p.s. which is a spread of 31 f.p.s.

Full auto

After velocity testing I tried the full-auto mode. This subgun fires as fast as the German MG42 from WWII, which I think might have been called the Devil’s zipper. It fires faster than the M16, but this Thompson IS NOT TOO FAST FOR ACCURACY. In fact the fast firing seems to make it more accurate! That’s an exaggeration, but a very slight one!

The individual BB holes (arrows) were shot during velocity testing from 8 feet distance. The two larger groups in the box were shot full auto from the same distance. Each of them holds 10-12 BBs.

It’s easy to shoot just five shots per burst. You just need to be quick on the trigger.

Shot count

I got about 110 shots with two CO2 cartridges. There were the 30 in the velocity test, plus the remainder of the H&N round balls after the 10 we checked for velocity. They were fired full-auto. Then there were two more 30-round strings shot full auto.

The last 20 rounds went out very slowly. Some didn’t even penetrate the cardboard target box. The cyclic rate (rate of fire) even decreased somewhat.

Summary

So far, so good. The M1A1 does have nice movement during firing but it’s not even as much as a 9mm pistol cartridge fired in a submachine gun. Therefore the gun does move while firing but is very easily held for a small group.

The trigger is heavy but positive. I think this gun will be very accurate.

Tom Gaylord (B.B. Pelletier)

Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

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