Odd ball Thompson SMG


January 17, 2006, 08:10 PM
I was watching an old early 30's crime movie the other night.
It was "The Big House" with Wallace Beery.

During the big prison break, Beery and the others break into the armory and arm themselves with rifles, pistols, and several Thompson submachine guns.

The gun Beery was using had an odd attachment I've never seen on a Thompson before.

It was a telescoping tube device attached to the mid-point of the barrel, with the other end attached to the actuator knob.

Clearly this blocked the sights of the gun.

When he fired it, the actuator moved the telescoping tube in and out of the front half.

Anyone have any idea what this was?

The only thing I can think of, was since this was the only Thompson I saw actually being fired, possibly it was some sort of blank firing device.

Possibly, there was a port into the barrel that used gas pressure to operate the bolt by moving the actuator back.

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January 17, 2006, 08:26 PM
I beleive what you saw was a very old muzzle break. Did It look like a box attached to the end of the barrel?

I'll try and find a picture.

January 17, 2006, 08:35 PM
no luck with the pics, I believe that they were an after market muzzle break that could be clipped to the end of the barrel and removed easily. I also believe that they are very rare, but have been shown in at least one pic from the 1920s or '30s (I saw it on 'Tales of the Gun').

January 17, 2006, 08:43 PM
No, this wasn't the box-like muzzle brake. That, I've seen.

This was a long telescoping tube attached to the MIDDLE of the barrel and going back to the actuator knob on the receiver.

At first, I thought it was some type of telescopic sight, until Beery fired it.

Jim K
January 17, 2006, 08:47 PM
FWIW, I took a look at some books on the Thompson, with pictures of TSMG's of that era and can't find anything that looks like what you described. Until late WWII, the TSMG already had a muzzle break as standard equipment, so I don't know why they would need another when shooting blanks. I would think a blank adapter would be inside the barrel or at the muzzle. The only thing I can think of that would look like that would be an attachment to use the vertical foregrip to cock the gun like a pump shotgun. I have never heard of such a thing, but it wouldn't be impossible.

If I get a chance to see the movie, I'll take a look.


chestnut ridge
January 17, 2006, 09:38 PM
There is a satire of The Big House; by Laurel and Hardy.
It is called Pardon Us. There are several scenes involving apparently
full auto thompsons. One scene shows a thompson with the strange
tube mounted much like a scout rifle scope. I thought it was some type
of optic sight. This movie is available now on dvd.

January 17, 2006, 09:43 PM
The only thing I can think of that would look like that would be an attachment to use the vertical foregrip to cock the gun like a pump shotgun.


That does seem reasonable, that little knob is hard to grab sometimes. With gloves on it's even worse.

January 18, 2006, 01:16 AM
No this attachment would make it HARDER to cock the gun.
It's NOT attached to the gun anywhere except the middle of the barrel and the actuator knob.

Imagine a thin tube with the front end attached to the middle of the barrel.
There is smaller diameter tube telescoping into the bigger tube.
This smaller tube attach's to the actuator knob.

When the gun fires, the actuator moves back and forth with the bolt, and the thin tube telescopes into the larger tube.

Again, the only possible purpose I can see would be as some sort of blank firing assist device.

This is the only time I've ever seen something like this, and possibly the Thompson was still new enough in 1930 that a better blank firing arrangement hadn't been developed.

One thing's certain: The gun was a 1921 model Thompson, and whatever the attachment was didn't slow it down any.
Every time Beery fired, cases POURED out the ejection port.

January 18, 2006, 02:25 AM
Sounds like some sort of device to slow the cycle rate down.

loose cannon
January 18, 2006, 03:44 AM
my wife a longtime tommygun fan had some big problems with the m1927 round knob so im putting together a special tommygun useing the kahr/auto ord m1 semiauto a extended boltknob and a m1927 verticle foregrip.

with 20 rd mags its to be her plinker/ranch defense carbine.

January 18, 2006, 10:36 AM

"Tracie Hill and the gang compiled a BIG list of movies with Thompsons in his newsletter some years ago. I know I have it somewhere. I'll hunt it up and, when time permits, I'll put 'em all up here. By the way, the movies that have the Thompson with the w-i-d-e open compensator (which I dubbed the "0" model), was a movie-made blank adaptor. It was an MGM gun. Tracie told me that at his house.
Frank: I hope you don't mind us posting this historical frivolity on the site. Brings back memories of Tommy-toting movies to us older f***s. There was one with Sinatra that I'm trying to remember.

January 18, 2006, 04:08 PM
If I recall correctly, The Thompson is blowback operated, which would not work well with blanks, if at all. The tube sounds like a crude conversion to gas operation, which can be tuned to operate quite well with blanks. I have never seen one, but that is what it sounds like to me.

Carl N. Brown
January 18, 2006, 04:54 PM
The blank firing attachment seen in some films is a square box muzzle
attachment very unlike the Cutts Compensator introduced about 1925;
the square blank attachment is very noticeable, so I would not be
surprised that some prop man would come up with a gas tube assist
to the actuator believing it would be less conspicuous.

Does anyone have The Big House on DVD?

Jim K
January 19, 2006, 12:36 AM
The Model 1921 and Model 1928A1 Thompsons are not actually direct blowback, as they have the Blish "lock". The M1 and M1A1 Thompsons are straight blowback. In point of fact, straight blowback guns are the easiest to adapt to blank firing. A simple muzzle constriction (usually screwed into the barrel and invisible from the outside) works very well. In the Thompson, a constrictor could be inserted into the Cutts Compensator without even altering the gun.


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