Umarex Thompson M1A1 Part 4

Umarex Thompson M1A1 Part 4

Select Fire and Performance

By Dennis Adler

Select fire is a great option on an air rifle like the Thompson M1A1 submachine gun especially since the M1A1 seems capable of maintaining tight groups even on full auto, more about this later. The same can’t be said for the legendary .45 ACP models which are notorious for muzzle rise. Again, never having fired one I can’t speak to that with any personal experience, but those who have fired them say muzzle rise with the big .45 Auto Thompson has to be managed. I have fired other types of smaller caliber weapons on full auto and 9mms have increasing muzzle rise, so a .45 Auto goes without saying. Accuracy with any automatic weapon not only comes down to a proper grip to control recoil but trigger pull and learning to fire short, accurate bursts, which is hard to do. CO2 models like the Thompson allow a level of practice that simply is not available in the centerfire world without owning a real select fire Thompson and going through a lot of .45 ACP ammo. Of course, if you have gone that far the cost of ammo is probably not a big consideration.

With the Umarex, you can experience a small sense of what that is like, and to my surprise, firing the M1A1 for the first time on full auto, and keeping my same POA and shooting off the shoulder from 21 feet, the groups fired in five- to six-shot bursts were not bad at all . I had a dozen rounds left in the magazine after my velocity tests and flipped the selector over to full auto, squared up on the same target (after photography) used for the velocity tests, which already had 10 hits at 1.25 inches, and put the last 12 rounds into a spread of 2.5 inches, with some pretty tightly overlapping hits on the first 10 rounds. My first short burst was pretty close to POA. The second burst (shooting to empty) began to drift higher and left, so even the CO2 model has a little muzzle rise on full auto.

The trigger pull is heavy but smooth at an average of 7.5 to 8.0 pounds with a 0.5 inch take up to break the shot. The sensation of the bolt action recoil (which will not function with an empty magazine and thus there is no waste of CO2), is not as great as the sound of the Thompson blazing away on full auto, and I think that will be a feature every airgun enthusiast will be keen on. You can cock the action with the charging handle and dry fire to practice trigger pull, but the CO2-powered action will not operate with an empty magazine.

Velocity and accuracy with Daisy Match Grade Precision Ground Shot

Will more expensive steel BBs gain a little extra mileage with the M1A1? I ran 10 through the chronograph and average velocity was 430 fps (though this was after running 30 rounds through the gun, with a dozen of them on full auto). Velocity is going to decrease as the CO2 is expended but you can expect to see this gun getting over 400 fps pretty much until the CO2 is almost gone. 

The important difference with the Match Grade is whether accuracy is improved. Again shooting from the shoulder at 21 feet, 10 rounds hitting just a bit left of POA went into 0.93 inches with a best 5-shot group, all overlapping just below the bullseye at 8 o’clock measuring 0.25 inches. Again, the M1A1 is impressive fired semi-auto with its basic military fixed battle sights. My correction for POI vs. POA would be under and inch up and right at 21 feet, I was just a little off on this test and shots went slightly low and left but still a satisfactory 10-shot group.

The only other steel BBs that I have found can make a slight difference in velocity and accuracy are Hornady Black Diamond black anodized BBs, which is usually my second go-to choice for velocity comparisons. Knowing that the test gun has already put about 50 rounds downrange in tests and has been in the magazine for three days, it will be interesting to see what kind of velocity I can get out of Black Diamond. Velocity was lower to start at 382 fps and the subsequent nine rounds dropped to 372 fps, 374, fps, 372 fps, 368 fps, 364 fps, 353 fps, 351 fps, 350 fps, ending with a low of 332 fps and I could definitely feel and hear the sound of the action changing with each shot, but accuracy did not suffer at all, and my 10-shot group with Black Diamond, shot through the chronograph off the shoulder at 21 feet, measured 0.93 inches with a best 5-round group all overlapping in a cut through the 10 and bottom of the bullseye at 0.43 inches. At least from this first full test, including 12 rounds on full auto, the average number of shots is going to be around 60.

To be fair to the Hornady, I loaded new CO2 and re-shot the chronograph test with the Black Diamond, and got a velocity spread with a high of 441 fps and an average velocity of 430 fps with a standard deviation of 5 fps. I also shot another target and my spread for 10 shots was 0.875 inches with a best 5-shot group at 0.375 inches.

The new Umarex Legends M1A1 may be the most accurate CO2 blowback action rifle to date equipped with a basic, period correct military peep sight.

In Part 5 we move everything back to 10 yards.