Wartime M1928A1 should it have a Forearm Re-enforcing Strap?

[Planejack]

In my efforts to make a Display of a WWII M1928A1 Thompson,  should it have the Re-enforcement Strap for the Forearm?  I’m looking to do a Thompson of the 1943 time period with the smooth barrel and “L” type rear sight.  I also have a Buttstock with the Re-enforcement cross bolt, but I’m certain that those would probably not have been used during that period?  

[robbo]

I have a M1A1 with the front strap. Not seen that on the 28's though.

[bob241]

1928  Thompsons used the grip mount  type shown below,  and does not require a front strap,

 

https://www.gunbroker.com/item/1093416315

[Frank I.]

The reinforcement strap was designed for M1A1 Thompsons with the "easier to manufacture" riveted grip mount, which was prone to breaking under stress from a carry sling. The strap reduced the stress placed on the mount. If the mount failed the foregrip would fall off.  The barrel needed to be removed to replace the grip mount.  

For pictures and details see American Thunder III pages 185 and 305

 

[Planejack]

OK to all who responded….it looks like a resounding “No” to the strap.  THANKNYOU for your input! 

 

[rpbcps]

With the introduction of M1A1, another cost cutting effort was the solid milled fore grip mount being repalced by a 3-piece riveted design, which, apparantly was a failure because the rearmost riveted part required a hole in the body of the grip mount near the front end of the receiver where the grip mount needed its maximum strength. A downward pull on the sling can bend the grip mount downward, away from the barrel.

To solve this problem, the forearm re-enforcing strap was fitted to the M1A1's, with the rivetted design fore grip mount, clamping the barrel and front end of the forearm together.

War time manufacturing sometimes creates an interesting dilemma. The design changes on the M1A1 grip mount, in an effort to reduce costs, created a requirement for a separate part to be manufactured to correct an issue that did not previously exist. This is a classic case of a penny saving modification, costing pounds to fix. 🙄

Edited March 14 by rpbcps
typo

[reconbob]

  To make a grip mount by machining it from a solid bar, bending it and heat treating it so it is a hardened spring is a difficult and time consuming process. 
 

The barrel band is a part that cost literally Pennies to make and a full wartime supply could be made in a week freeing up those milling machines that had been spending lengthy, time consuming, and expensive effort on a nothing part.

Streamlining production time and costs was done throughout industry during the war. M1903A3 rifle vs. M1903 with numerous short cuts - two groove barrels vs. 4 groove. Stamped bands vs. milled bands, simplified rear sight with stamped base vs. intricate M1903 sight, Steel cased ammo, And look at the M1 Thompson - no fins, stamped sight, cheap grip mount, and eventually you have the simple, cheap and effective Grease Gun.

The cheap grip mount created a “problem” solved by a 10 cent part. There was a problem with the milled grip mount - it took too long to make.

Was the changing of the rear sight from the ridiculously intricate, complex, and expensive Lyman 55B to a functional. and cheap stamped sight also solving a problem that did not exist? 

Bob

Edited March 14 by reconbob

[rpbcps]

Good point, never thought of it, from that angle.

[Doug Quaid]

I love Thompsons, but it's hard to deny that the 1921 was over-designed and over-built.

Can anyone explain why the gun needed a cantilever mount that pushed up on the exact center of a cooling fin?  That's something that is done on bench rest target rifles to make the barrel vibration more uniform.  That is a really fancy mount for a subgun.

You can go down the list -

blish lock:  not really needed.

cutts compensator: not really needed

barrel fins: not really needed

ladder sight: not really needed

etc

operationally, even the drums were a bust compared to the 30 rnd stick mag.

When you can make something simpler and it actually works better, it's hard to deny that it's an improvement.

I bought an M1A1 just for the heck of it, but once I had it, I had to grudgingly admit to myself that it's actually a better gun in the practical sense.  Sure it's more of baloney sandwich, compared to the Veal Cordon Bleu that the 21 is, but it's a war weapon.

 

[Rekraps]

21 minutes ago, Doug Quaid said:

I love Thompsons, but it's hard to deny that the 1921 was over-designed and over-built.

Can anyone explain why the gun needed a cantilever mount that pushed up on the exact center of a cooling fin?  That's something that is done on bench rest target rifles to make the barrel vibration more uniform.  That is a really fancy mount for a subgun.

You can go down the list -

blish lock:  not really needed.

cutts compensator: not really needed

barrel fins: not really needed

ladder sight: not really needed

etc

operationally, even the drums were a bust compared to the 30 rnd stick mag.

When you can make something simpler and it actually works better, it's hard to deny that it's an improvement.

I bought an M1A1 just for the heck of it, but once I had it, I had to grudgingly admit to myself that it's actually a better gun in the practical sense.  Sure it's more of baloney sandwich, compared to the Veal Cordon Bleu that the 21 is, but it's a war weapon.

 

Excellent observations my friend. Look at the evolution of the PPSH (from the PPD) and you'll see that Americans were not the only ones looking to make more for less. And... those cheap PPSH's killed lots and lots of Germans. 

[Doug Quaid]

9 minutes ago, Rekraps said:

Excellent observations my friend. Look at the evolution of the PPSH (from the PPD) and you'll see that Americans were not the only ones looking to make more for less. And... those cheap PPSH's killed lots and lots of Germans. 

 

What I want to know is why so many WWI guns had such tiny open sights.  They must have had some really sharp eyeballs back then.


 

[Countryboy77]

On 3/14/2025 at 6:04 PM, reconbob said:

  To make a grip mount by machining it from a solid bar, bending it and heat treating it so it is a hardened spring is a difficult and time consuming process. 
 

The barrel band is a part that cost literally Pennies to make and a full wartime supply could be made in a week freeing up those milling machines that had been spending lengthy, time consuming, and expensive effort on a nothing part.

Streamlining production time and costs was done throughout industry during the war. M1903A3 rifle vs. M1903 with numerous short cuts - two groove barrels vs. 4 groove. Stamped bands vs. milled bands, simplified rear sight with stamped base vs. intricate M1903 sight, Steel cased ammo, And look at the M1 Thompson - no fins, stamped sight, cheap grip mount, and eventually you have the simple, cheap and effective Grease Gun.

The cheap grip mount created a “problem” solved by a 10 cent part. There was a problem with the milled grip mount - it took too long to make.

Was the changing of the rear sight from the ridiculously intricate, complex, and expensive Lyman 55B to a functional. and cheap stamped sight also solving a problem that did not exist? 

Bob

So Basically in a nutshell Every Thompson after the Colt 1921s-1928s and Early Savage are just cheaper and cheaper versions not really solving any Problems but just making it Cheaper and cheaper till they finally leave the Thompson for the M3? I mean thats how History seems to read.Goverment doesnt give the best to everyone,it gives what you need to get by,by the cheapest contract.Well I guess it gave us a variety of different of looks we seen throughout the years .Variations are cool ,keeps the hobby interesting.

[Lewisfan]

Maybe not 1943 production, but here's a late 1942 production gun.  High serial number Savage.

[reconbob]

    The only submachine gun I can think  of that existed when the Thompson was developed was the MP-18. The Thompson was the first submachine gun  developed with the intention to be marketed and sold vs. a military trench warfare gun. The desire to exploit the Blish patents caused the bronze lock to be used and all of the bells and whistles - semi and full auto, bolt hold open on empty mag, 600 yd. rear sight, detachable stock, etc. were all thought to be great ideas. The gun was all-new. It had never been used in a war, or for anything. If the Thompson did not exist,  how long would it have taken to end up with the Grease Gun? And would it have been the Grease Gun as we know it? Or would we have ended up with .45 ACP Stens?

Bob

Edited March 17 by reconbob

[Rekraps]

On 3/16/2025 at 1:37 PM, Doug Quaid said:

 

What I want to know is why so many WWI guns had such tiny open sights.  They must have had some really sharp eyeballs back then.


 

Really? We all know that people had little eyes back then. Some kind of genetic thing-a-mal-bob going on. Red Dye #4 eliminated that....

[2ndArmored]

Some didn't use their eyes anyway.

 

[Planejack]

That 1942 produced Savage made M1928A1 is exactly what I’m trying to make for my display gun using an 80% receiver and original parts.  I’ve managed to secure all required, but the finishing done on my 80% receiver is too glossy.  Looks like yours was sandblasted prior to Dulite finishing….and looks like your drum mag (L mag) is a Seymour made example?

[Merry Ploughboy]

On 3/16/2025 at 12:55 PM, Doug Quaid said:

...

Blish lock:  not really needed.

...
 

And yet now, some form of delayed blowback mechanism is considered a "must have" in virtually all pistol caliber carbine type firearms.  Otherwise the gun is considered 'too harsh', 'too much recoil', 'not smooth enough', 'jumpy', 'bouncy', 'not soft', 'not gentle',...

Go figure.

MHO, YMMV, etc.

[Countryboy77]

On 3/16/2025 at 4:14 PM, Lewisfan said:

Maybe not 1943 production, but here's a late 1942 production gun.  High serial number Savage.

Very cool,I love it when people keep the proper issued sights on their gun no matter what they are. Wasnt swapped with a lyman ladder and finned barrel.Very nice

[Countryboy77]

On 3/16/2025 at 11:55 AM, Doug Quaid said:

I love Thompsons, but it's hard to deny that the 1921 was over-designed and over-built.

Can anyone explain why the gun needed a cantilever mount that pushed up on the exact center of a cooling fin?  That's something that is done on bench rest target rifles to make the barrel vibration more uniform.  That is a really fancy mount for a subgun.

You can go down the list -

blish lock:  not really needed.

cutts compensator: not really needed

barrel fins: not really needed

ladder sight: not really needed

etc

operationally, even the drums were a bust compared to the 30 rnd stick mag.

When you can make something simpler and it actually works better, it's hard to deny that it's an improvement.

I bought an M1A1 just for the heck of it, but once I had it, I had to grudgingly admit to myself that it's actually a better gun in the practical sense.  Sure it's more of baloney sandwich, compared to the Veal Cordon Bleu that the 21 is, but it's a war weapon.

 

Ian from forgotten weapons did a video shootingthe thompsom 1921ac the thompson 1928a1 and the Thompson M1 and he thought the M1 was going to be the best of allwhen in fact he was surprised that the 1921 with its higher rate of fire was a better shooting weapon as the harmonics of the weapon really purred with the 1921. Even the 1928a1 shot better he said.I know the blish lock and compensator isnt needed for the gun to run,but they shure do feel better.Its a different shooting impulse( i like them all) but i would never say the M1 was superrior neigther the greasegun eigther.They were just less expensive ro produce.

[Doug Quaid]

22 hours ago, Merry Ploughboy said:

And yet now, some form of delayed blowback mechanism is considered a "must have" in virtually all pistol caliber carbine type firearms.  Otherwise the gun is considered 'too harsh', 'too much recoil', 'not smooth enough', 'jumpy', 'bouncy', 'not soft', 'not gentle',...

Go figure.

MHO, YMMV, etc.

I used to use a buffer to speed up my UZI, but I got used to the slower, bouncier ROF and don't use a buffer anymore.

I have both a 1928 and an M1A1 and I find the M1A1 to be really easy to shoot accurately.  There was no "jumpy gun" learning curve, I just started chewing up targets with it.  

 

[Doug Quaid]

7 hours ago, Countryboy77 said:

Ian from forgotten weapons did a video shootingthe thompsom 1921ac the thompson 1928a1 and the Thompson M1 and he thought the M1 was going to be the best of allwhen in fact he was surprised that the 1921 with its higher rate of fire was a better shooting weapon as the harmonics of the weapon really purred with the 1921. Even the 1928a1 shot better he said.I know the blish lock and compensator isnt needed for the gun to run,but they shure do feel better.Its a different shooting impulse( i like them all) but i would never say the M1 was superrior neigther the greasegun eigther.They were just less expensive ro produce.

Those youtube guys are kind of hilarious, they always base their evaluations on a few mags of ammo at the range.   Like that means anything.

Right now there is this big thing among the youtube neckbeards to harshly criticize the Thompson in general.  It makes people feel like an expert to have a contrary opinion to the foolish masses.  

If only we had some other source of data to evaluate guns with... like maybe a global war.   Wouldn't it be swell if the Thompson had been used in a big war in say Europe or maybe even some jungle fighting in southeast Asia?  Then we would have a real world acid test of its various qualities.  Oh well...

Edited March 22 by Doug Quaid

[Doug Quaid]

On 3/16/2025 at 8:58 PM, reconbob said:

    The only submachine gun I can think  of that existed when the Thompson was developed was the MP-18. The Thompson was the first submachine gun  developed with the intention to be marketed and sold vs. a military trench warfare gun. The desire to exploit the Blish patents caused the bronze lock to be used and all of the bells and whistles - semi and full auto, bolt hold open on empty mag, 600 yd. rear sight, detachable stock, etc. were all thought to be great ideas. The gun was all-new. It had never been used in a war, or for anything. If the Thompson did not exist,  how long would it have taken to end up with the Grease Gun? And would it have been the Grease Gun as we know it? Or would we have ended up with .45 ACP Stens?

Bob

Sure, 20/20 hindsight is a universal gift that all humans possess.

It does seem to me that they got target fixation on making the Thompson be overdesigned and overbuilt.  I say that because Savage didn't have to conduct massive scientific experiments to strip all the frou-frou off the gun.

Once AOC had the 1921 prototype in hand, couldn't they have given it the same critical eye that Savage did?  There is no magic to what Savage did.

Does an 11 lb gun that shoots 45acp need a compensator?   The free recoil energy number on the gun is in the range of a 22 hornet.  

I know this is sacrilege, but maybe it could have used another design cycle in 1921 as opposed to 1942.

Edited March 22 by Doug Quaid

[Merry Ploughboy]

8 hours ago, Countryboy77 said:

Ian from forgotten weapons did a video shootingthe thompsom 1921ac the thompson 1928a1 and the Thompson M1 and he thought the M1 was going to be the best of allwhen in fact he was surprised that the 1921 with its higher rate of fire was a better shooting weapon as the harmonics of the weapon really purred with the 1921. Even the 1928a1 shot better he said.I know the blish lock and compensator isnt needed for the gun to run,but they shure do feel better.Its a different shooting impulse( i like them all) but i would never say the M1 was superrior neigther the greasegun eigther.They were just less expensive ro produce.

I wish that Ian would have also done ROF runs with the recoil springs in the '28 and M1/M1A1 swapped to determine what the spring effect was on the ROF.  I'm pretty sure he likes to do such things, so perhaps he was under orders from the owner to not take the guns apart.

In any case, I do recognize that delayed blowback is generally of more effect and value in closed bolt firearms configurations, though there's a party or two that have put together a delayed blowback MAC SMG using the CMMG rotary system, FWEIW.

MHO, YMMV, etc.