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Underwood Subcontractors A-Z

Printed From: The Carbine Collector's Club
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Printed Date: Jan 27 2023 at 7:01am
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Topic: Underwood Subcontractors A-Z
Posted By: New2brass
Subject: Underwood Subcontractors A-Z
Date Posted: Mar 06 2021 at 12:37pm


Underwood Subcontractors A-Z

By Dan Pinto

This article is focused only on the subcontracted marked parts used by Underwood.


The marking of carbine parts to identify the prime contractor was a requirement of the Ordnance Department. This way if there was an issue with parts, Ordnance would know which prime contractor was responsible. The prime contractor is assumed to be the manufacturer of subcontracted parts for legal and financial reasons. Ordnance was not concerned with the subcontractors as their contracts were direct with the prime contractors.(1)

It was up to the prime contractor to assign markings to the subcontractors for accountability if they chose to do so. Ordnance did lay out a system of marking where the letter code was the prime contractor first followed by the subcontractor (Q-LT). I am sure many of you have seen this document and noted the Ordnance approved marking system was not widely adhered to and with the addition of other prime contractors this became an issue.  (2)

Early on, Ordnance recommended that the system Inland used should be adopted, where parts were marked subcontractor to prime contractor (LT-Q). (1)

The system had its issues when Standard Products came in and we see some parts where the S code comes first as well as SS with a number.  (3)

Inland had repetition of the same letter for different subcontractors that made different parts, B was used on the gas cylinder, firing pin, recoil plate, and sear but each part was made by a different company. Further, some companies that produced the same item for more than one prime contractor did not always have the same subcontractor code. An example would be firing pins made by Olsen Brothers Machine Tool & Saw Company which used OB B variations for I.B.M. but used SI for Inland.

With Underwood, we see only one letter in the alphabet was assigned to each subcontractor with no duplication. Later we see some codes with two letters for the subcontractor which will be discussed below. Having one letter code for each subcontractor would lead to some logistical issues when two companies had the same first letter in their company name.

Logic would dictate that letters would have been assigned in the order that the contracts were secured with the subcontractor or soon thereafter and not necessarily when we see those parts showing up.

The first letter of the company name was used if available. If not, then another part of the company name could be used. If that did not work, it appears that Underwood would assign the first letter available alphabetically.

We first notice this issue with the subcontracted receivers. In February 1943, the following 4 contractors were recommended to Underwood as subcontractors. (4) (5)

Intertype Corporation, Brooklyn NY, was given the first set of numbers in Underwood’s second serial number block. The letter I was already in use for International Silver.  The speculation is that Underwood used part of the InterType name and T became their code with Underwood.

Universal Windings, Cranston RI, was given the second set of numbers in Underwood’s second serial number block. Underwood used U for another subcontractor, Union Hardware. Using W for Windings seems logical.

United Shoe Machinery Corporation, Beverly MA, was given the third set of numbers in Underwood’s second block of serial numbers.  The letter U, as discussed, was used by Union Hardware. Here the S for Shoe appears logical.

Singer Manufacturing Company, Bridgeport CT, was given the fourth set of numbers in Underwood’s second block. The S code was now taken by United Shoe Machinery Corporation. M was not feasible for Manufacturing as most companies had the words manufacturing or machinery in their names. Also, M was in use for Marlin Firearms Company. It has been theorized that B could have been for Bridgeport.  The problem with this is that no other code matched a city of the subcontractor, and then why not B for Brooklyn where Intertype was located.

It is more reasonable that B was the first available letter not yet used. To follow the theory of alphabetical letter assignments the A would have had to be assigned before Singer received their contract. 


Mag Catch

Parker Wire Goods/ Parker Manufacturing Company



Parker Wire Goods/ Parker Manufacturing Company



Singer Manufacturing. Co.



Possibly Petroleum Heat and Power. Read Below


F pin

Bruce McDonald


Ft. Sight

Prestole Div. of Detroit Harvester

F in Heart ·U·


Frederick Hart & Co.



Graham Mfg. Co.



Possibly Howe Machinery. Read Below

IU, IU in Circle


International Silver



International Silver



Talon Inc.



Cinaudagraph Co.



M.S. Little Co.


Stock & HG

Marlin Firearms



Marlin Firearms


Firing Pin

Nolan Machine Co.

.O..U. In Circle


Oneida Ltd.

P U, P-U

Stock & HG

Pedersen Brothers



Utica Cutlery



United Shoe Machinery Corporation



United Shoe Machinery Corporation



Intertype Corp



Union Hardware



Universal Windings Co.



Universal Windings Co.



Universal Windings Co.


Firing Pin

Universal Windings Co.



Universal Windings Co.

Ψ ·U·


Neptune Meter Co.


Stock & HG

Lumb Woodworking

S. & C.  U

Stock & HG

Sprague & Carleton


Ft. Sight

Simpro Mfg. Co.


Underwood used ·U· or ·U· for parts they manufactured and are not covered in the chart for brevity

AU: Parker Wire Goods was a subcontractor to Underwood. They were the sole Underwood subcontractor for magazine catches and one of two subcontractors for their recoil plates. Underwood also manufactured their own recoil plates and magazine catches.

The only reported subcontracted magazine catch is marked AU. Therefore, the magazine catch would have to be Parker Wire Goods. Parker also made the magazine catches and recoil plates for I.B.M.

In comparing Parker Recoil Plates made for I.B.M. (PR-B), N.P.M. (PN), and Inland (PI) to the AU recoil plate it can be observed that they all have similar machining direction and marking on all faces. All the letter codes are in the same location on the side of the tang. Coupled with the magazine catch and absent any notable variations on the recoil plates makes a convincing case that the AU recoil plate was made by Parker Mfg. and that A was their sole assigned code.

Notice how all the shown machining on the AU and PR-B recoil plates is left and right but the on Underwood made recoil plate, the tang on both sides has a curved diagonal pattern, as does the bottom. The top surface has markings going up and down as shown.

The Parker recoil plate contract to Underwood may have been spurred with the advent of the new recoil plate. To follow the theory of alphabetical letter assignments the A would have had to be assigned before Singer (B) received a contract.

This brings us to the unknown C·U· and H.U. bolts. Four companies were subcontracted to make bolts for Underwood. SU was used on bolts made by United Shoe and the WU bolt was made by Universal Windings. This leaves Petroleum Heat & Power and Howe Machinery that we do not know which code they were assigned. 

The case can be made for either company to be assigned H. In respect to Petroleum Heat & Power, the P was already in use for Pedersen Brothers, so H could be for Heat. The H for Howe Machinery would seem obvious, but if the H were already taken then it would default to the first available letter assignment.

Petroleum Heat & Power Company was formed in the 1920s and considered a major concern, having offices in Boston Mass, Providence RI, and New York NY. Their factory was in Stamford, Connecticut. They were a pioneer in the oil-burner field and manufactured the industrial oil-burning apparatus to replace coal-burning units. They also sold and delivered the fuel oil to their new customers.

Howe Machinery Company president Stanley A. Carlson sat on the War Production Board. Howe Machinery organized the Passaic Home Workshop Pool to subcontract and produce essential war materiel which predated the M1 carbine production. It was a co-op of home workshops that worked together for the war effort.

In comparing two original finish H.U. marked bolts, I see several inconsistencies in the machining as well as fit and finish. The critical areas are most probably to specifications. However, the inconsistencies and evidence of hand filing and deburring are not something you would expect from a production shop.

Having only one C·U· bolt, I was not able to make an equal comparison but will say the machining was much nicer than that of the H.U. bolt.


Two H.U. bolts. The lug on the left measures narrower and it is accentuated by heavy deburring or hand filing of the edges. Also, note the lower-left area on front of the lug, the right has more angle to the cut.



Here you can see the wear patterns are different between the two. Also, note the web thickness variation between the lug and the extractor plunger cut. These variations are probably due to the machining fixture not holding the bolts in the same position every time causing inconsistent results.


At the backside of the lug, we again see different wear patterns from interaction with the slide. Also, notice the rougher machine finish on the left. This could be from a dull tool bit, but also possible that it was different feed rates, setups or done on different lathes.

Though not absolute proof, I would say that the H.U. bolt was most likely produced through Howe Machinery and even more possible that several of the home shops did piece work on the bolts based on the inconsistencies. Home shops would probably not have access to the same modern machinery of a big company with things like automatic feeds which give a consistent finish.

Considering that Mr. Carlson sat on the War Production Board it would seem he took care of his own first and Howe was assigned the H code.

This would default the C·U· bolt to Petroleum Heat & Power

DU firing pins have long been observed on original carbines. The reporting on firing pins and extractors is less than other components; this is due to many rightfully not disassembling a bolt absent the proper tools as well as reporting of carbines at gun shows or auctions where bolts could not be taken apart.

There are three known subcontractors of firing pins to Underwood: Universal Windings (WU), Bruce MacDonald Company and Nolan Machine Company. It is unknown which code DU was assigned, as there were no reports of any other firing pin marking on original Underwood Carbines.

Recently we had a report of a loose N-U type 1 firing pin. This report prompted another report of type 2 N-U firing pin." rel="nofollow -

Nolan Machine Company produced firing pins for NPM (N-N), QHMC (N-Q), and Underwood. There is also a firing pin marked N-S which is most probably is a yet-to-be-found Nolan subcontract to Standard Products. 

There is not much machining to compare on firing pins but sometimes there are obvious differences if you look close enough. The machining and marking location as well as the fonts are all consistent on these and would suggest that N-U is Nolan for Underwood

This leaves DU for Bruce MacDonald. The Bruce MacDonald company also made firing pins for Inland marked BI. Unfortunately, I was unable to source a good example of the BI Inland firing pin for observation.

Being that the type 1 DU firing pin was observed early on in Underwood carbines it would suggest that the D is from MacDonald rather than D being the first available unused letter.

In January 1943, the Carbine Committee’s office located in Underwood’s head offices in New York City received prototype fabricated stamped front sights made by Prestole Division of Detroit Harvester. The new front sight was incorporated in May 1943. (6)

Prestole reportedly provided these front sights to I.B.M. (PO B), Q.H.M.C (PO Q), Saginaw Grand Rapids (PD over SG), and Underwood.

Looking at QHMC, the only subcontracted stamped front sights were from Prestol, and we see them with barrel dates starting about September 1943. Markings of PO B, EU, and PO Q as well as unmarked are reported on QHMC carbines, yet there are no Carbine Industry Integration Committee transfers documented. It is quite possible that the subcontractor just sent parts where needed regardless of the markings. This could be especially true after the prime contractors received word that carbine contracts would soon be canceled.

Comparing the EU to the PO Q and PO B front sights,  It becomes clear that the EU sight was produced by Prestole. The earlier Prestole sights were marked on the ear, later the marking was moved to the base behind the sight blade. Underwood must have had plenty of milled front sights because we do not see the stamped sights till late production.

The E code would have been assigned to Prestole as the first available letter as P was already taken.

The only other stamped and brazed sights used by Underwood were those marked SI U by Simpro Manufacturing Company. Simpro also supplied front sights to I.B.M. (SI B) and reportedly to Saginaw in Grand Rapids. However, they probably never delivered as no code has been documented.

The SI U marking is one of only four markings that do not fall in line with the A-Z markings as there is more than one letter used for the subcontractor. This is probably due to them being latecomers to Underwood and these companies were already producing for other prime contractors.

Lumb Woodworking provided stocks to I.B.M. (LW B). They also later supplied stocks to Underwood which were marked LW or LW U

Sprague & Carlton was a stock supplier to I.B.M. (SC B). These are rarely encountered on Underwood and marked S.&C. U. Sprague & Carlton used only birch for their stocks.

The addition of Lumb Woodworking and Sprague & Carlton stocks for Underwood were probably prompted by the stock shortage in late 1943.

Both companies received Ordnance contracts for stock assemblies as replacement or spares when their contracts were terminated with the prime contractors.

The last marking that does not follow the system are the triggers made by Neptune Meter Company, which used their trademark trident for identification. The mark was Ψ ·U·

There was only one other subcontracted trigger for Underwood, and it has the JU marking. The only other known company is Talon Inc. in Meadville PA. Talon also made triggers for I.B.M. (TB). In comparing triggers in general there are several items to observe. Here we will look at a few of the obvious feature differences.

The LT trigger made by Ludlow Typograph Company is shown for comparison and did not make triggers for Underwood.


Note the shape of the bottom of the trigger.


The Ludlow Typograph Company trigger on the left has an obvious difference just above the blue line. Both the TB and JU have a chamfered edge at the bottom where the LT is to a rounded point

In comparing a TB to JU there are enough similarities in the machining and shape to say that the JU was made by Talon. The one observation that stands out is the different size fonts used. The T was already in use for Intertype. This would mean that J was the first unassigned letter available.

There were two known subcontractors for Underwood extractors, MU being Marlin Firearms and the KU extractor is the unknown.

Cinaudagraph Company in Stamford, CT. is listed as the only other subcontractor to Underwood for extractors. In looking into Cinaudagraph Company they had several ordnance contracts, but the only known carbine part is the extractor for Underwood. Therefore, there is no other extractor to compare it to. The C was previously assigned and K being the first unassigned letter.

So by now you you probably understand the mystery of the Q.U. marking for Utica Cutlery to Underwood and had nothing to do with Q.H.M.C.

Five letter markings that were not represented for Underwood marked parts: R, V, X, Y, Z

The Jewelry Crafts War Production Pool in New York, NY received a contract to make recoil plates for Underwood. I am unaware of any other coded recoil plate that could be for an Underwood subcontractor.

Looking into Jewelry Crafts I find no contracts for wartime contracts for M1 carbine parts or any other war materiel. It is possible that they did not have any Ordnance contracts, or if they did it may have been below the threshold of reporting. If they had any subcontracts, then the records would have been with the prime contractor.

 In searching I found only one mention of them in Congressional Records “Report of Smaller War Plants Corporation” as becoming an approved vendor. The report was in mid-1943 and covered the previous 6 months. It is unclear just when they were approved and may have never got into production by the time it was known that carbine contracts were to be canceled.

Unanswered Questions:

There has been unsubstantiated reports of other markings which may have been in error.

If anyone has observed a recoil plate marked JU or PU or a front sight marked PU, please share a picture and any information with the club.

Looking forward to the discussion on my theory of the Underwood markings.



      1. Carbine Club Newsletter 206-7

      2. Carbine Club Newsletter 202-1

      3. Carbine Club Newsletter 384-15

      4. War Baby 368

      5. Carbine Club Newsletter CCNL 182 conjecture on lettering

      6. War Baby pg. 114, 370

War Baby 3 pg. 1110 Marking of Parts.

Links of interest:" rel="nofollow -" rel="nofollow -

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Posted By: Beezer
Date Posted: Mar 06 2021 at 3:56pm
I’ve always found it fascinating how so many companies geared up for the war efforts to make all kinds of parts. 

Thanks for posting.  My Underwood has a Singer receiver. 

Posted By: Mschro79
Date Posted: Mar 06 2021 at 6:35pm
Thanks for the great info. This really makes me want to get my data sheet on my Underwood done! 

Go Navy! USNS Mercy DS/DS
Best movie line ever! 'Don't piss down my back and tell me it's rainin!' -Fletcher

Posted By: New2brass
Date Posted: Mar 07 2021 at 1:37pm
Here is one for you minutia guys to go with the link above
Neptune Meter made water meters. They also had their own foundries to cast the covers and meter bodies

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Posted By: SSNPingjockey
Date Posted: Mar 23 2021 at 10:17am
Dan....your argument and evidence for the assigning of letter designations appears pretty dang solid to me!  Very much appreciate your thoughts, research, and narrative on this.  You solved some mysteries and answered some questions that I had.

As UEF fans, have to love the Neptune marked triggers and the Frederick Hart slides.  Even if you happen to have one of each at work in a rifle, have to also have each on-hand in the parts bin.

QUESTION:  What are your thoughts on Lumb Woodworking marked stocks?

You mentioned LW and LW-U marked stocks both being UEF specific.  Obviously, the LW-U is UEF just like the LW-B is IBM, but I thought I had read or heard discussed that the stocks solely marked LW were war-time replacement stocks?  As a matter of personal observation, I have not seen a great many LW marked stocks, but feel like the ones that I have seen from memory were mostly on Underwoods, but I look a little closer at Underwoods, so maybe that accounts for it.

Anyway...thanks again!

USN Retired

Posted By: New2brass
Date Posted: Mar 23 2021 at 5:00pm
I did not delve to far into the stocks as the point of the article was the markings and how late in production there were some markings that do not follow the system as I see it.

Lumb Woodworking did have a contract to produce spare stocks in March 1944, when most contractors were wrapping up production. These would be M1 stocks only.

This was followed by two later contracts in January and February 1945. I would suspect these stocks might be the latest revision and suitable for M1 and M2 carbines.

With the shortage of stocks was it possible that Lumb had more than would be required for I.B.M.s requirements? Did they get a contract with Underwood in addition to their I.B.M. contract and they stamped a B or U based on where they were going and some were missed?

There have been a few reports of LW marked stocks that have the CC in a rectangular box with the GHD/UEF. Absent the stamps you would have to scrutinize the stock as to which type it was which could rule out some based on timeline of how produced.

I have observed on LW stock that appears to have been modified by removing the bridge and cutout for a selector switch. It does have the beefier ledge for the recoil plate support.

I did not mention the Underwood use of Trimble stocks. It is unknown if these were a transfers from NPM or directly from Trimble to Underwood.
with the mad shuffle to complete as many carbines as possible I am sure some requirments of markings were missed.

If anyone has one of these with clear CC it would be helpful to know if there is any marking signifying that it was a transfer.

If anyone has a LW stock please take a look at it and let us know which type it is.

Best, Dan

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Posted By: bzh362
Date Posted: Mar 23 2021 at 9:41pm
I have an LW stock with "p in a square" proof on the bottom of the grip. No crossed cannons, but on the left side, there is "MR" stamped into the wood under the sling well. Not on an Underwood, but figured I'd share since I have no idea how that stock got on my gun. 

It is unmodified M1 as far as I can tell.

Thanks for the article and pictures! Fun read :) 

Posted By: Smokpole
Date Posted: Mar 24 2021 at 7:55pm
IIRC the MR stands for Mount Rainier Arsenal.

OGCA Life member
NRA Life member
Ashtabula Rod and Gun Life member

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