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Printed From: The Carbine Collector's Club
Category: The Club
Forum Name: Newsworthy Items
Forum Description: Newsletters and Featured Carbines
Printed Date: Dec 07 2021 at 5:24pm
Software Version: Web Wiz Forums 12.01 -

Posted By: Newsman2
Subject: FEATURED CARBINE: IBM 3937627
Date Posted: Mar 11 2017 at 10:42pm" rel="nofollow - Download PDF

March 2017-A

International Business Machine (I.B.M.) Serial Number 3937627


This IBM was a DCM gun originally purchased from the LetterKenny Army Depot in Chambersburg, Pa. The receipt is shown below and yes, it was sold for $20.


The oval cut stock is marked LW-B (Lumb Woodworking Co Inc. of Poughkeepsie, NY) in the sling well with the expected cartouche.

View of the barreled action including the trigger housing and slide. Note the 26 ½ coil hammer spring used in all I.B.M. carbines.


The type 1 rear sight is marked GE-Q and S on the other side (the leaf is unmarked). GE-Q sights were made by Gerrand Co. of Chicago Illinois for Quality Hardware. They have been reported on other IBM carbines but no documentation exist of a lateral transfer between Quality Hardware and IBM. The rear sight staking and sight pin staking is also shown.

Below is an overhead view of the rear sight. Note the different types of dovetail staking on the left and right side.

The receiver ring marked U.S CARBINE CAL. .30 MI as shown below. Note the single staking on the gas piston screw.



A close up of the wrist (marked with W) and stock nose. Numerous original appearing, late IBM carbines were reported with a single letter stamped on the wrist. See CCNL 345 for for more information. The reason for the letters is unknown. Could they be inspector marks? Perhaps they are inspector marks from the LetterKenny or other depots? More information is needed. Collectors, please report your IBM carbines to the club. The type 2 band has four weld scars. The P proof mark is also shown; note how close it is to the nose of the stock.

The recoil plate is marked PR-B (Parker Manufacturing Co. of Worcester Ma.) and is common on original carbines. The recoil plate screw is of the late type.


The handguard is also marked LW-B (Lumb Woodworking Co Inc. of Poughkeepsie, NY). The oiler is marked IS for International Silver.


Note the increased dwell on the AOB (Auto Ordnance of Bridgeport, Conn.) marked slide (see CCNL 363). It appears many late IBM carbines have slides with increased dwell, but no 7160091 number stamp. Also note the double stamps slide, in this case stamped EE. Could double stamped slides denote increased dwell?  More research is needed.

The trigger housing is marked BE-B on the right side and is of the braised type.

The trigger housing contains the following parts: Sear marked SW-B (Star Watch Case Co. of Ludington, Mich.), magazine catch marked PR-B (Parker Mfg. Co. - Parker Wire Goods Co. of Worcester, Mass.)safety marked EPB (Eaton Pond Co. of Springfield, Mass.),Trigger marked PD B (Paradise Mach. Co. of West New York, NJ) and the hammer is marked AMB (Art Metal Works of Newark, N.J.).

The round bolt is marked AOB (Auto Ordnance of Bridgepost, Conn.) upside down on the right lug and an H is stamped on the left.  Note the type 3 firing pin and extractor.

Top view and close up of trigger housing including single hammer strike mark and type 2 sear marked SW-B (Star Watch Case Co. of Ludington, Mich.).

IBM Barrel Proof Mark

A close up view of the IBM Barrel Proof mark. It appears to be sideways. If others have serial numbers in this range, please report the orientation of the P mark.


Multiple views of the I.B.M. SI B (Simpro Mfg. Co. of Newark N.J.) front sight and undated I.B.M. Corp barrel.  Undated barrels have been reported in the 3.79-3.96 range. Note the front sight key retention is held in place by the milled notch also called the "hacksaw" cut. The barrel crown is of the rounded type. Sometime during production, the way barrel crowns were finished changed. Early barrel have a flat crown, later ones rounded (CCNL 345).

Side views of the SI B front sight.  Note the bluing and indentations on either side of the pin.

The type 2 barrel band has a single slash \ mark. Type 2 barrel bands on IBM's have been reported as unmarked, /, \ and //.  Close up of the 4 weld scars type 2 barrel band.

The butt plate is also shown. Two type of butt plates have been observed, type A (CCNL 329-4) and type B (CCNL 94-5). This butt plate is the type A "step" pattern.

Data Sheet

Thanks to owner of this fine example of a late IBM carbine, Steve Manning.


Copyright: The Carbine Collector’s Club©

Posted By: m1a1fan
Date Posted: Mar 12 2017 at 5:34pm
Fantastic example of a late IBM.  Great pictures of the parts especially those which are blued.  Did not realize the barrel crown shape changed as manufacturing progressed.  This article also pointed me to a few CCNL's about IBM's which I've missed.  Very informative.  Thanks!

Posted By: patrickduis
Date Posted: Mar 13 2017 at 3:55am
Very nice find. Way more original than my I.B.M. .30m1

.30M1: 1943 IBM 3x1943-1944 Inland 1943 Underwood
1918 Springfield 1903
1918 Eddystone M1917
1911A1 Colt & Ithaca
S&W Victory
1944 Swiss K31

Posted By: Impala12
Date Posted: Mar 25 2017 at 5:45pm
Nice carbine

I have an S'G'. Stock is not original, but the rest is.

Posted By: pvc4440
Date Posted: Mar 28 2017 at 4:56pm
Makes me want to work on my 10-43 IBM

Posted By: ibm1jh
Date Posted: Mar 31 2017 at 10:37am
REALLY cool example of a late IBM carbine. Outstanding pictures and notes. This is way better than the paper CCNLs. Thanks!

John H

Posted By: m1a1fan
Date Posted: Mar 31 2017 at 1:48pm
Hopefully there are more fine examples of IBM's to come. Any maker would do but I am particularly fond of IBM's.

Posted By: New2brass
Date Posted: Mar 31 2017 at 4:39pm
Originally posted by ibm1jh ibm1jh wrote:

REALLY cool example of a late IBM carbine. Outstanding pictures and notes. This is way better than the paper CCNLs. Thanks!
Ah! so now we see why the forum can be better than paper! Plus you can download and print a copy. A win-win

Posted By: kar6666
Date Posted: Jul 22 2017 at 6:00pm
A friend of mine had one very much like that one. It has probably been 15 or more years since I last saw it. But what really impressed me was the contrast in the color of the parts and I see this shows the same contrast. It was a really a nice looking carbine. He had all ten manufactures plus a few extras but the late I.B.M. was the best looking carbine he had to me. The thing that bugged me the most was his had a adjustable rear sight and he replaced it with a flip sight. It was his only carbine that didn't have a flip sight and he thought it would look better if they all had flip sights. As hard as I tried I couldn't talk him out of it.

Posted By: m1a1fan
Date Posted: Jul 31 2017 at 10:47pm
Haven't run into all that many IBM's with dated barrels. Not sure why but haven't seen many original IBM's with barrels after 10-43.

Posted By: ibm1jh
Date Posted: Aug 01 2017 at 8:45am
I think IBM only dated their barrels from July to December, 1943. The earliest dated barrel I have seen in 7-43, and the latest 12-43. I have seen several 9-43s and 10-43s. By January, 1944, they stopped dating them (unless someone has a later example). And then they stopped production altogether in Spring of 1944. I have always been partial to a dated barrel, though.

John H

Posted By: m1a1fan
Date Posted: Aug 01 2017 at 8:05pm
Have seen them up to 10-43. So far, of the dated barrels, 10-43 seems to be the most "common". Another 10-43 just sold recently. Have yet to see an 11 or 12 of 43. Someday, hopefully. A 12-43 AO IBM, that would be a find.

Posted By: Doug Bathurst
Date Posted: Nov 27 2017 at 8:22am
Great information and pics! Thanks for posting. I need to do the same with a couple of mine

Posted By: Johnboy490
Date Posted: Dec 11 2017 at 6:09pm
I just traded for a IBM serial number 377xxxx that has. Barrel date of 11-43 ibm barrel with the flaming bomb, I don’t know how. To post pics of it, thanks in advance.

Posted By: Ghostman
Date Posted: Dec 15 2017 at 4:00pm
the single punch mark on the gas piston outer frame, looks like it was done by an field armorer or other owner through out the years, replacing the piston and/or nut. Note the 3 rectangular marks on each flat of the nut, those were the original staking marks.

Retired Army 1987-2008
4th ID Mech, 11th ACR, 25th ID light, 82nd Abn, 101st Abn/AAsslt, 160th SOAR
Helicopter Dr.
VCDL member
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Weapons & History Enthusiast

Posted By: Dave Tennent
Date Posted: Dec 15 2017 at 8:33pm
My original IBM has an identical single punch mark on the gas piston.


Posted By: m1a1fan
Date Posted: Dec 15 2017 at 9:31pm
I once read a random post that no original carbines had stake marks on the gas piston nut, but no pictures were offered. What's strange to me is those three areas are described here specifically for staking." rel="nofollow -

Why put them there if the nut wasn't supposed to be staked? What tool was used? Was it chisel like instrument, some type of punch or both?

All of the original IBM's I've seen have the same type punch stake mark like Dave's and the OP's.

Note to collectors. If you have an original carbine inspected, sometimes part of that process is to check the nut to see if it is loose. If it is, politely ask to have it tightened and not staked again.

Posted By: Dave Tennent
Date Posted: Dec 15 2017 at 9:57pm
My 3791003 is also staked with one punch although I don't have a photo of it.


Posted By: m1a1fan
Date Posted: Dec 16 2017 at 12:36am
Found a few more pics of IBM staking for reference...a 3.72 and 3.70

Posted By: Carl Bine
Date Posted: Aug 15 2020 at 4:40pm
Just put money down on a local 395XXXX late IBM in all original condition. Almost with all the same marked parts as the above. Incredible almost new shape (with correct patina) and very tight. Excited! Your photos (in addition to the books) helped. Thanks.

Posted By: Smokpole
Date Posted: Aug 18 2020 at 5:49pm
I find the sight marking interesting. I've seen 4 other IBM carbines with relatively close serial numbers that I believe were all original and all of them had the GE-Q flip sights. While there is no documentation, it seems obvious that a significant number of those sights were used in a fairly narrow serial number range that this carbine falls into.

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

Posted By: Carl Bine
Date Posted: Aug 18 2020 at 6:28pm
My forthcoming late IBM seems to be all-original and the right side of the rear sight is FO B. #3950667. Staked the same way. Will post pictures next week.

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