Different Thompson?

This is a what if for a weapon, if it isn't appropriate hear then we can move it.

What if the Thompson SMG were chambered for the .357 Magnum?
The .357 is awsome in a long barrel handgun, exceptional in a levergun, I just wonder how different it would make the Thompson.
It has the weight to manage recoil, it is an accurate round, and with a 158 or 200 gr bullit at 1400+/- fps it would hit really hard.
Maybe that would be getting into the relm of the M-1 Carbine territory and might have been redundant?
Any opinions?

 

It would be damned difficult to keep on target, and would kill your shoulder. There's a reason the BAR was invented.

 

I think one other thing that might interfere with this idea is the chamber pressures produced by the different rounds. The .45 ACP produces about 21,000 psi max., while the .357 is way up there at about 46,000. To produce a weapon that could withstand that sort of pressure, and at automatic speeds might have made the already heavy Thompson completely untenable as a SMG.

The little .30 Carbine produces a respectable 40,000 psi (approximately) I believe, and its 20 inch barrel allows it to convert that pressure into just under 2,000 fps with a 110 grain bullet. Not to shabby really.

 

The Blish system used in the 1928 model probably could have been tuned to a higher pressure round than the .45 ACP but a rimmed cartridge like the .357 would have caused problems in the areas of magazine design & feeding. I've seen mentioned that Auto-Ordnance had experimented w/ other calibers in the Thompson SMG including the .38 ACP/ .38 Super. The Super gives .357 Magnum-like performance & is a rimless round to boot. The Super would have been a flatter shooting round than the .45 ACP but not as much so as the .30 Carbine.

 

But the Blish lock had been eliminated by the time of the M1A1, and then the whole system would have needed to be remodeled or something. And if that were done it wouldn't really be a Thompson anymore, would it?

Personally I don't think a .357 would be much of an improvement with all the intendent problems of the round in this application. And as you (Old Schoolr) mentioned, other rounds had been experimented with, and NOT accepted by John Thompson himself. Of course his own participation in the "Thompson-LeGarde" ballistics tests in Chicago (1904 or '08 ?) might have "colored" his opinion somewhat.

It was those tests which influenced the Browning .45 ACP afterall, and with that as a standard round already in the military he worked up his famous SMG "trench-broom" using that round.

 

In the 1920 -1930's there was no way the US military would have adopted the Thompson in a caliber other than the existing .45 ACP & that probably played as much in Thompson's choice as anything else. As it was the USMC picked up on the SMG faster than the US Army & many of the Thompson's the Marines had were purchased by the US Postal Service. & never returned to them.
Had a customer stepped forward pre WWII w/ an order for a large number of Thompson's in a caliber other than .45 ACP I'm sure A-O would have obliged. IIRC they had done some preliminary engineering for the Super, 9mm Parabellum, 9mm Mauser Export & .22 RF.

 

While I don’t doubt that the Auto Ordinance people would have been more than happy to attempt to re-chamber their weapon to any round; a large order (as you mention) would have required by a foreign government in order to do so.

It must be remembered that by the time the .357 Magnum (the original post tenet) showed up the world was in a worldwide depression since the .357 Magnum cartridge wasn’t released until 1934. And even then the .357 S&W round was in competitive response to the Colt .38 Super that had shown up in the late ‘20s, and which was/is in itself a remarkable round.

The Colt .38 Super had higher muzzle velocity than the "Luger" 9x19mm, and in some loadings more kinetic energy than the standard .45 ACP. I personally think that would have made a "killer" combination for the Tommy Gun, but then again what do I know.

Then think of what would have shown up later in the cheaper M3A1? A less expensive "lead pump" using the Colt .38 Super with the ability to alter to the 9mm "Luger" with simple parts changes. Heck only the receiver, spring, and mag feed might have been needed, the barrels would have nearly matched!

 

Call it what you will; but, the .45 Thompson and 1911 came out of the need for increased "knock down" power that the standard issue .38's weren't providing at the time. the 230 Gr ACP was far superior to the 158gr rounds that are the most common loads for .38/.357.

The trend after the Spanish American War was "bigger is better" and the military had already decided that the .45 ACP was to become the new standard pistol round. Colt even submitted a .38 version of the 1911 in the trials.

Brad

 

The statement is often made that US Army adopted the .45 ACP due to the .38 not doing the job in the Philippines. That is true but it is important note which version of .38 cartridge was in use at that time. That cartridge is the .38 LC which is less powerful than the .38 Special, the .38 Super, the 9x19mm & especially the .357 Magnum. The fact that the .38 LC cartridge is underpowered doesn’t damn any & all other .38’s. Apples to apples; no one would say that the .30-06 round performs at par w/ the .30 Carbine because they are both .30 caliber.
The debate over whether “the 230 Gr ACP was far superior to the 158gr rounds that are the most common loads for .38/.357.” has gone on for years & probably will continue for as long as people discuss firearms. The Marshall and Sanow reports (which use data collected from law enforcement shootings) give the .357 a better “one shot stop” rating than the .45ACP. Reports came back during the Korean war of the .357 having superior penetration on Chinese winter clothing than the .45. Note; the M & S studies rate a number of different bullet types & weights in each caliber.
Dr. Fackler’s writings give the edge to the .45. Search the net & you’ll find that the M & S reports are “disputed”. Disputed by whom? The “big bore” lobby most of whom live by the gospel of Fackler (& like me are probably NOT in the business of having to shoot people). Neither Marshall or Sanow were out to prove the superiority of either round, their intent was to study effectiveness of common cartridges in real world usage. I’ve read that Marshall carries either a .45 ACP or 9x19mm as a PDW & feels that both are effective.
I personally wouldn’t feel under-gunned w/ the .357 or the .45. The biggest factor in stopping an attacker is bullet placement & a grazing wound in a limb is not a stopping shot w/ either caliber.
The OP’s question of a .38 SMG making the .30 Carbine redundant is an interesting idea as is Brndirt’s suggestion of a .38 Super M3 “Greasegun” even if we know that it never happened.

 

Different loadings of the .357 Mag. have substantially more knock down power than the .45, I also realize that a full metal jacket would have to be used in the military arena, but 200 gr bullets are not uncommon in the 357 and would be very potent at high velocities.
Since I open the post, I will throw out one more cartridge although not around at the time, the 10mm in its original full power loading may be even better. But, I realize this is WWII and I wont remark anymore in that direction.
I spoke to a WWII sgt who carried the .357 in both WWII and Korea. In both wars he said his life and anothers was saved because he had a side arm. In WWII he wacked a German who tried to stop the jeep he was driving an officer around in, his M-1 carbine was in a rack, but he drew his pistol as he came to a stop. The Korean incident he dispatched two NK while he was squatting over a hole he had just dug and couldn't reach his M-1 Garand. In both cases he said one shot dropped each "bad guy". I know it's not the .357 Thompson, but you don't hear many 357 war stories from that time period.

 

The standard 357 is a rimmed cartridge and won't function in an auto loader using a box type magazine. A new rimless case would be needed. A couple of comparisons. A 357 using 158 gr bullets can be loaded from 1250fps to 1400fps without reaching max pressures. This gives a 50yd energy of 450 to 560 fp. A 45 using 180gr bullets can be loaded from 850 to 950 fps before pressure limits. This bullet energy ranges from 243 to 294 fp. The 45 230gr loads from 750 to 850 giving 50yd energies of 268 to 342 fp. Might be slightly off as I did a quick look up

 

Rimmed cartriges can be and are used in box magazines. Many .22s have box mags, and last time I checked the Desert Eagle is still chambered for the .44 and .357 and uses a box mag. So the mag wouldn't be an issue. I don't think pressures would be a problem either. The recoil would also be managable, as I have fired a 357 lever gun and it does't weigh near what a "tommygun" does.

 

I think the problem here is that the Desert Eagle design isn't a recoil driven mechanism, but a gas operated unit. It isn't the magazine, it is the recycling/loading system.

"Unlike most pistols, the barrel does not move during firing. When a round is fired, gases are ported out through a small hole in the barrel near the breech. These travel forward through a small tube under the barrel, to a cylinder near the front of the barrel. The separate bolt carrier/slide has a small piston on the front that fits into this cylinder; when the gases reach the cylinder they push the piston rearward. The bolt carrier rides rearward on two rails on either side of the barrel, operating the mechanism. Its rotating bolt strongly resembles that of the M16 series of rifles, while the fixed gas cylinder/moving piston resemble those of the Ruger Mini-14 carbine (the original patent used a captive piston similar to the M14 rifle)."

Goto:

Desert Eagle: Facts, Discussion Forum, and Encyclopedia Article

Which puts us into an entirely new design problem you see.

 

I have a relative with the original Ruger .44 Mag carbine, it utilizes a straight blowback design and it kicks less than an M-1 carbine. It would not take much modification to chamber the Thompson in .357 Mag. The driving force like anything else is the market. There just isn't a market for a magnum smg of this weight and proportion. With todays modern recoil systems there are better choices. I just thought it would be an interesting thought to have a Thompson that you could hunt deer with. (In semi auto mode of course.)

 

One thing to consider w/ the Ruger is that is uses a underbarrel tubular magazine like a shotgun. This eliminates any potential feeding problems that would come about from using a rimmrd round in a box magazine.
The original Thompson w/ the Blish system could probably be used w/ the short-lived .45 Winchester Magnum round which is more or less a stretched .45 ACP.

 

I still don't think the box mag is a major issue, the .22 is a rimmed cartride and I have had 20 round box mags for my 10/22 that never have feed problems. You are right though that the rimless or actually recessed rimmed cartriges are much easier to use in the magazines.

 

The new version of the Ruger uses a detachable magazine, but they have also gone to the mini-14 style action.