Top of Receiver Nose Pin Punch Mark on M1 and M1928A1 TSMG's

[NavyEngineer]

 

I have never read anything specific about these marks pertaining to Thompsons. However,

during the time that the Thompsons were made and serviced it was a standard procedure to put

a prick punch mark on a receiver whenever the receiver was rebarrelled. It is NOT a mark caused

by a hardness tester. A Rockwell tester leaves a tiny mark as seen on the photo of the bolt above,

not a deep recess as seen on the receivers and barrels. The Rockwell B scale uses a 1/16" ball

penetrator. The C scale uses a pointed diamond penetrator. So the punch mark is too deep and

not rounded to be the B scale, and far too deep (again, see tiny marks on bolt) to be the C scale.

All spare Thompson barrels were proof fired and marked with a P at top dead center. I assume

that when a gun was rebarrelled it was proof fired and center punched in the middle of the P and

also the top front of the receiver right behind the P.

How long this procedure was followed I do not know. I think it got its start with the M1903

Springfiled rifles which were in service for over 20 years, many of which had several barrels

fitted over time as evidenced by multiple punch marks on the right side of the front receiver

ring below the serial number.

 

Bob

Bob,

 

I was hoping you would see this, and provide your insight. It makes complete sense. Thank you for your post.

 

David Albert

dalbert@sturmgewehr.com

Bob, Thank you for providing correct information. An old veteran told me many years ago that with the large number of manufacturers building parts for small arms in WWII, Rockwell hardness testing was frequently used to verify the hardness of steel was within specs. It's been years since I've performed the test myself, and I didn't realize how large those dimples were in the photos. I apologize.

[dalbert]

 

Are there guns that do not have these marks that were not refinished that might cover them up?

Does anyone have a military Thompson without the punch mark on the top of the receiver nose?

 

The only photo I was able to find that did not have a punch mark on the nose was a Savage Commercial in the 27,000 serial number range. All the rest were military TSMG's with a punch mark, Savage in the middle, and AO on the left side.

 

David Albert

dalbert@sturmgewehr.com

[av8tr]

Mine are punched the same.

 

 

Savage 1928A1, punched in the middle, AOC M1, punched on the left side. The Savage is pictured a few posts up. Sorry the M1 is a bit blurry.

 

 

 

 

[DZelenka]

Mine are punched the same.

 

 

Savage 1928A1, punched in the middle, AOC M1, punched on the left side. The Savage is pictured a few posts up. Sorry the M1 is a bit blurry.

 

 

pix558148906.jpg

And the AOC has a serif P, proof mark on the barrel. It is blurry. I assume it is punched on the P?

[DZelenka]

 

 

Are there guns that do not have these marks that were not refinished that might cover them up?

Does anyone have a military Thompson without the punch mark on the top of the receiver nose?

 

The only photo I was able to find that did not have a punch mark on the nose was a Savage Commercial in the 27,000 serial number range. All the rest were military TSMG's with a punch mark, Savage in the middle, and AO on the left side.

 

David Albert

dalbert@sturmgewehr.com

David,

 

What do the tops of the rivets on your AOC guns look like?

[av8tr]

 

Mine are punched the same.

 

 

Savage 1928A1, punched in the middle, AOC M1, punched on the left side. The Savage is pictured a few posts up. Sorry the M1 is a bit blurry.

 

 

pix558148906.jpg

And the AOC has a serif P, proof mark on the barrel. It is blurry. I assume it is punched on the P?

Yep, punched on the P.

[reconbob]

The M1 picture posted above by av8tr I consider to be a textbook example

of punch marking to indicate barrel change. The barrel and receiver have different

finishes. It appears that the receiver is parkerized (so it's been reworked) and the

barrel is blued which in the finish found on all spare barrels. If the gun was factory

New it would have a blue/black oxide finish on all parts.

 

Bob

[av8tr]

The finish on the barrel and receiver are definitely different on my M1. The barrel is absolutely more "blue" than the receiver. I do not have another picture on my computer showing them together. Here is a picture of the receiver. By the way, the lower is a Savage lower, so the gun is definitely not the way it came out of the factory.

 

 

But, on the 1928A1, the finish is the same. And, some knowledgeable people have opined that it has its original barrel. And, its receiver and barrel are punched.

Edited January 23, 2019 by av8tr

[DZelenka]

The M1 picture posted above by av8tr I consider to be a textbook example

of punch marking to indicate barrel change. The barrel and receiver have different

finishes. It appears that the receiver is parkerized (so it's been reworked) and the

barrel is blued which in the finish found on all spare barrels. If the gun was factory

New it would have a blue/black oxide finish on all parts.

 

Bob

If the punch mark indicates a barrel change, why are AOC receivers punched on the left side and Savage receivers punched in the center? If you were correct, wouldn't you expect to see the location vary based upon the re-barreler, not the brand of upper? A more plausible explanation would be that they were puncher during the original manufacturing process as part of a military requirement (we do not see similar punch marks on commercial Savage guns).

[reconbob]

So all AOC M1928A1 Thompsons have a center punch mark on the left top of the receiver?

And all Savage M1928A1 Thompsons have a center punch mark in the center/top of the receiver?

In other words, all M1928A1 Thompsons have a center punch mark, its just a question of where it

is on the receiver. Again, I have not paid much attention to this (but I will now) but my initial thought

is that many receivers have no punch mark.

 

Bob

[dalbert]

So all AOC M1928A1 Thompsons have a center punch mark on the left top of the receiver?

And all Savage M1928A1 Thompsons have a center punch mark in the center/top of the receiver?

In other words, all M1928A1 Thompsons have a center punch mark, its just a question of where it

is on the receiver. Again, I have not paid much attention to this (but I will now) but my initial thought

is that many receivers have no punch mark.

 

Bob

 

Bob,

 

My initial thought was also that many receivers would have no punch mark. However, I found that assumption incorrect in my limited number of different photos on file (a dozen or so) that clearly showed the top of the receiver nose. I only found one early "Commercial" Savage that didn't have the mark. The photos I checked were consistent with the punch marks we have reviewed so far...Savage in the middle, and AO on the left side.

 

David Albert

dalbert@sturmgewehr.com

[av8tr]

I might add that I don't think it is limited to 1928A1's. Based on my M1, (AOC punched on the left) they would be included as well.

[DZelenka]

I believe it is all military Thompsons made by AOC and Savage.

[bug]

 

So all AOC M1928A1 Thompsons have a center punch mark on the left top of the receiver?

And all Savage M1928A1 Thompsons have a center punch mark in the center/top of the receiver?

In other words, all M1928A1 Thompsons have a center punch mark, its just a question of where it

is on the receiver. Again, I have not paid much attention to this (but I will now) but my initial thought

is that many receivers have no punch mark.

 

Bob

 

Bob,

 

My initial thought was also that many receivers would have no punch mark. However, I found that assumption incorrect in my limited number of different photos on file (a dozen or so) that clearly showed the top of the receiver nose. I only found one early "Commercial" Savage that didn't have the mark. The photos I checked were consistent with the punch marks we have reviewed so far...Savage in the middle, and AO on the left side.

 

David Albert

dalbert@sturmgewehr.com

 

My 16K SavCom has no punch mark nor does it have a P on the barrel. Quite a few here have early Savage guns. What do they see? Also, there was a thread here a good while ago that touched on varying amounts of finish discoloration on the front third, or so, of TSMG receivers. Someone either suggested or stated that the front of the receivers were heat treated and that that was the cause. I searched but couldn't find the thread. I don't recall if any proof was offered for the nature of the heat treatment or which models were treated. My thought was, if this is true, perhaps the punch mark was some form of hardness test.

 

Bob D

[gijive]

While searching through some Thompson barrels I have, I came across a couple that were taken off guns that don't have the punch mark in the center of the "P" proof. Based on the placement of the sight on one barrel the "P" proof was actually at about the Seven O' Clock position. This barrel is a Stevens barrel with no "Draw Line".

 

The first set of pictures is the Stevens barrel that was taken off of an old DeWat M1 Thompson.

 

 

Stevens "S" at Three O' Clock position. Proof "P" at about the Seven O' Clock position. DeWatted barrel hole.

 

 

DeWatted barrel hole at Six O' Clock position Rusted front sight.

and "P" Proof at about Seven O' Clock.

 

The second barrel is a Savage "S" M1 barrel that has the cut for the sight pin. The barrel has been refinished with black oxide since the drilled cut is blackened and not bare metal. There is no "Draw Line" on this barrel and it also has some other unusual punch marks. The Savage "S" is about at the Seven O' Clock position, another mark at Six O' Clock and additional marks at the Eight O' Clock position. The "P" is at the Twelve O' Clock position and has a small punch at near the base of the "P".

 

 

"P" Proof at Twelve O' Clock. Drilled cut for sight pin. Savage "S" with additional punch marks.

 

No "Draw Line" at Threee O' Clock position.

 

I thought these might be of interest in light of the current discussion on punch marks during barrel replacement.

[full auto 45]

Found a pic of my M1 without having to go to the safe. You can see the punch mark on the receiver and the "P" on the barrel. Number 511626 M1A1 originally, then new bolt and the A1 X'd out.

 

Are there guns that do not have these marks that were not refinished that might cover them up?

Does anyone have a military Thompson without the punch mark on the top of the receiver nose?

 

[DZelenka]

While searching through some Thompson barrels I have, I came across a couple that were taken off guns that don't have the punch mark in the center of the "P" proof. Based on the placement of the sight on one barrel the "P" proof was actually at about the Seven O' Clock position. This barrel is a Stevens barrel with no "Draw Line".

 

The first set of pictures is the Stevens barrel that was taken off of an old DeWat M1 Thompson.

 

Stevens M1 Barrel-Take Off-1.jpg Stevens M1 Barrel-Take Off-2.jpg Stevens M1 Barrel-Take Off-4.jpg

 

Stevens "S" at Three O' Clock position. Proof "P" at about the Seven O' Clock position. DeWatted barrel hole.

 

Stevens M1 Barrel-Take Off-5.jpg Stevens M1 Barrel-Take Off-6.jpg

 

DeWatted barrel hole at Six O' Clock position Rusted front sight.

and "P" Proof at about Seven O' Clock.

 

The second barrel is a Savage "S" M1 barrel that has the cut for the sight pin. The barrel has been refinished with black oxide since the drilled cut is blackened and not bare metal. There is no "Draw Line" on this barrel and it also has some other unusual punch marks. The Savage "S" is about at the Seven O' Clock position, another mark at Six O' Clock and additional marks at the Eight O' Clock position. The "P" is at the Twelve O' Clock position and has a small punch at near the base of the "P".

 

Savage M1 Barrel-Take Off-2.jpg Savage M1 Barrel-Take Off-1.jpg Savage M1 Barrel-Take Off-3.jpg

 

"P" Proof at Twelve O' Clock. Drilled cut for sight pin. Savage "S" with additional punch marks.

 

Savage M1 Barrel-Take Off-4.jpg

No "Draw Line" at Threee O' Clock position.

 

I thought these might be of interest in light of the current discussion on punch marks during barrel replacement.

The Stevens barrel is clearly a replacement. The P is readable from the muzzle. All of the original barrels that I have seen are readable from the breach. The M1 take off has the P at 12 o'clock and it is punched in the loop albeit lightly. My bet is that is an original barrel that was taken off.

 

I have 3 new in the wrap barrels. If I recall correctly, the one or two I unwrapped had a P readable from the muzzle. I think that is an important distinction. We really need a few surveys. I haven't looked at a hell of a lot of these guns but some of the details I am seeing are holding fairly consistently.

[gijive]

"The Stevens barrel is clearly a replacement. The P is readable from the muzzle. All of the original barrels that I have seen are readable from the breach. The M1 take off has the P at 12 o'clock and it is punched in the loop albeit lightly. My bet is that is an original barrel that was taken off."

 

"I have 3 new in the wrap barrels. If I recall correctly, the one or two I unwrapped had a P readable from the muzzle. I think that is an important distinction. We really need a few surveys. I haven't looked at a hell of a lot of these guns but some of the details I am seeing are holding fairly consistently."

 

DZelenka,

 

I don't know if you saw the barrels in this link to an older post. What do you think about this Savage barrel?

 

 

 

[DZelenka]

"The Stevens barrel is clearly a replacement. The P is readable from the muzzle. All of the original barrels that I have seen are readable from the breach. The M1 take off has the P at 12 o'clock and it is punched in the loop albeit lightly. My bet is that is an original barrel that was taken off."

 

"I have 3 new in the wrap barrels. If I recall correctly, the one or two I unwrapped had a P readable from the muzzle. I think that is an important distinction. We really need a few surveys. I haven't looked at a hell of a lot of these guns but some of the details I am seeing are holding fairly consistently."

 

DZelenka,

O

I don't know if you saw the barrels in this link to an older post. What do you think about this Savage barrel?

 

Savage finned barrel-1.jpg

 

Savage finned barrel-2.jpg

 

Savage finned barrel-3.jpg

Honestly, I have looked at more smooth barrels than finned. But because of the fact that the P has not been punched, I’d say it’s a replacement.

 

Dan

[gijive]

Dan,

 

I agree definitely a replacement barrel. The muzzle is threaded for the compensator but not drilled for the pin. I thought you might be interested in the position of the P on the barrel collar.

[DZelenka]

Always. By the way, how is it positioned on an original barrel? Is it punched in the loop? Like I said, I don't have much experience with finned barrels.

[pgreen]

 I love your collection!

[Rekraps]

On 1/12/2019 at 2:41 PM, dalbert said:

Is the punch mark that is seen in both the photos below something that was done as part of an arsenal rework? I noticed it on am M1A1, and an M1928A1 Thompson. I just don't recall anything being discussed or written about such a marking. please correct me if it's mentioned in a book.

 

Here is is (kind of blurry) on an M1A1 Thompson. The barrel has also been punched in the same manner, inside of the "P."

 

 

Here's one from an M1928A1 Thompson.

 

 

Any information you can provide is appreciated. Thanks!

 

David Albert

dalbert@sturmgewehr.com

 

My 1928A1 is punched exactly like this, top left shoulder, very small punch, no other marks.

[Rekraps]

On 1/27/2019 at 9:42 AM, gijive said:

While searching through some Thompson barrels I have, I came across a couple that were taken off guns that don't have the punch mark in the center of the "P" proof. Based on the placement of the sight on one barrel the "P" proof was actually at about the Seven O' Clock position. This barrel is a Stevens barrel with no "Draw Line".

 

The first set of pictures is the Stevens barrel that was taken off of an old DeWat M1 Thompson.

 

 

Stevens "S" at Three O' Clock position. Proof "P" at about the Seven O' Clock position. DeWatted barrel hole.

 

 

DeWatted barrel hole at Six O' Clock position Rusted front sight.

and "P" Proof at about Seven O' Clock.

 

The second barrel is a Savage "S" M1 barrel that has the cut for the sight pin. The barrel has been refinished with black oxide since the drilled cut is blackened and not bare metal. There is no "Draw Line" on this barrel and it also has some other unusual punch marks. The Savage "S" is about at the Seven O' Clock position, another mark at Six O' Clock and additional marks at the Eight O' Clock position. The "P" is at the Twelve O' Clock position and has a small punch at near the base of the "P".

 

 

"P" Proof at Twelve O' Clock. Drilled cut for sight pin. Savage "S" with additional punch marks.

 

No "Draw Line" at Threee O' Clock position.

 

I thought these might be of interest in light of the current discussion on punch marks during barrel replacement.

So this thread ended without any clear consensus on the punch marks. My 1928 has a single tiny punch mark on the left side of the shoulder (AOC gun) and only an alignment mark on the barrel collar. It seems that everyone has a shoulder punch mark (or at least those who have responded) with apparent replacement barrels having both a "P" and a punch within the "P". So, it seems logical that the punch marks would be for hardness testing, or proof testing.

 

[anjong-ni]

To go back a few posts, is it really true that "all Thompson replacement barrels were test-fired"?

How? In a fixture?  Live ammo? Why? To burnish-them-in or something?

Manufacturing was pretty advanced at the time.

Making a lot of simple gun-barrels all exactly alike was easily accomplished by 1942.

Is it true that ALL 55,000 (in 3 years) Packard Merlins were assembled, run 8 hours, then stripped down to the last component and checked for perfection?

Seems like all this testing, if actually done... was slow and expensive. There was a war on...    Phil