The U.S. Caliber .30 Carbines


The Caliber .30 Carbine - Barrel Manufacturers

The Basics Here
The U.S. Caliber .30 CarbinesThe Carbine ManufacturersThe Barrel ManufacturersParts, Variations & Markings
Carbine NomenclatureThe Serial NumbersThe Stocks & HandguardsPost WWII Ordnance Operations

U.S. Caliber .30 Carbine Barrels & Barrel Manufacturers

U.S. Caliber .30 Carbine Barrel Characteristics
Lands & Groves: 4
Rifling: 1 right hand turn in 20 inches
Rifling Method: Broach or Button
Gas Cylinder: Integral or Swaged
Original Finish: Blued or Parkerized
*measured from the muzzle to the end of the skirt

Main Sections you will find on this page:

  • Barrel Manufacturers
  • Barrel Markings
  • Importer Markings
  • Barrel Characteristics

Barrel Manufacturers

During WWII

Prime contractors who manufactured their own barrels
  • Inland Division of General Motors
  • Winchester Repeating Arms
  • Underwood-Elliott-Fisher
  • Rock-Ola Manufacturing Company
  • Saginaw of Saginaw, MI
  • International Business Machines

Prime contractors who did not manufacture their own barrels (total of approx. 1,243,463 M1's)

  • Quality Hardware (359,666 M1's)
  • National Postal Meter (413,017 M1's)
  • Standard Products (247,160 M1's)
  • Saginaw Grand Rapids (223,620 M1's)
  • Irwin-Pedersen Arms (refer Saginaw Grand Rapids)

These companies were supplied with barrels manufactured by Inland, Winchester, Underwood, Rock-Ola, IBM and two
additional contractors hired to manufacture only barrels (Buffalo Arms and Marlin Firearms). Saginaw Grand Rapids
was also supplied with barrels by the Saginaw facility in Saginaw, MI. During 1943 alone, Underwood-Elliott-Fisher
provided over 500,000 barrels to the four prime contractors who did not make their own barrels.

Manufacturers contracted for Barrels only

Buffalo Arms

Buffalo, New York

   Manufacturers Mark:BUFFALO ARMS
(top of barrel, aft of front sight)
   Barrels Manufactured for:National Postal Meter
Quality Hardware
  • Instead of the name Buffalo Arms, the letters BA have been found on a few barrels

  • A few post war barrels have been found with forged BA letters

Marlin Firearms

North Haven, Connecticut

   Manufacturers Mark:MARLIN
(top of barrel, aft of front sight)
   Barrels Manufactured for:National Postal Meter

Subcontracted Barrels

Brown-Lipe-Chapin Division
General Motors Corporation

Syracuse, New York

   Manufacturers Mark:BI
(on flat between chamber & gas cylinder)
   Barrels Manufactured for:Inland Division
General Motors Corporation
  • BI found on front of swaged gas cylinders indicate the gas cylinder
    was made by B & P Motor Company, not Brown-Lipe-Chapin


Springfield Armory

Springfield, Massachusetts

   Time Period:1950-1954
   Manufacturers Mark:SA
(top of barrel, aft of front sight)
   Quantity Manufactured:454,761
   Barrels Manufactured for:replacement barrels
  • Some of original SA barrels had the Ordnance crossed cannons logo stamped on the barrel flat. Some of these do not have the SA markings on top of the barrel.

Herlo Engineering Corporation

Hawthorne, California

    Herlo manufactured .30 Caliber Carbine barrels under government contract from 1971-1974. Many, if not all, of the chambers were chrome lined after having been chambered. This caused the chamber headspace to be outside government specifications (short chambered). Difficulty in correcting the dimensions due to the hard chrome, in addition to improper dimensions in the front sight area and gas chamber, caused the government to reject ALL of the Herlo barrels.

    Since 1974 various private companies have been selling these barrels. Many of these companies have altered the barrels in an effort to make them function properly, including removal of the chrome lining. Some of these barrels have been found to have forged government acceptance marks. A few companies have managed to refurbish these barrels and make them safe.

    Given the totality of the history of these barrels and the efforts to correct them, unless you have the ability to verify the barrel is within accepted specifications, it would be wise to avoid on buying one. The potential for problems is high.

   Time Period:1970-1972
   Manufacturers Mark:HC
(on flat between chamber & gas cylinder)
   Quantity Manufactured:70,000+
(none accepted by government)
   Barrels Manufactured for:replacement barrels
  • 5557154HC on barrel flat is the part number and manufacturers mark

    But one example of markings found on a barrel
    manufactured by Herlo Engineering Corp.

    Most Herlo barrels do not have this marking.
    Those that do, it is believed to have been forged by an unscrupulous seller.

  • Above markings usually include a month, year, and lot number

  • If an Ordnance or government acceptance mark is present, it's not genuine

Barrel Markings

    Things you should know:

  • Not all manufacturers placed their markings in the same location as the other manufacturers

  • Not all barrels have dates, some barrels have partial dates

  • Finished and marked barrels were occasionally provided by one prime contractor to another prime contractor

Many manufacturers placed the month and year the barrel was manufactured directly below the manufacturers mark. This practice varied over time with some barrels having only partial date markings and some having no date at all. Proof of inspection marks can often be found along the top of the barrel farther from the muzzle than the manufacturers mark. Proof marks included the letter P in different sizes.

All barrel manufacturers under contract to U.S. Army Ordnance marked their barrels with either their name or manufacturers mark. The most common location for this marking was on top of the barrel approximately 2" from the muzzle. Markings used by some of the barrel manufacturers slightly varied over time.

The carbine was usually assembled and tested within 3 weeks of the barrel date.
Barrels were critical in supply, often hours away from shutting down the assembly line for lack of supply.

The photographs below should not be used to compare the differences in size and dimensions of barrel characteristics between manufacturers.
The illusion was created by the camera lens focal length, a slight angle, and/or it's distance from the barrel.

Inland Mfg Div.
General Motors


Saginaw S.G. Div.
General Motors

I.B.M. Corp.

(small W)

proof was oval
with PW logo


(upside down)

Orientation of the manufacturer markings, and date if it's present, are usually with the top of the digits facing the muzzle with the words/date running from left to right. However, barrels manufactured by Buffalo Arms (Buffalo Arms or sometimes B.A.) or Springfield Armory (SA) have been found upside down or sideways to the normal orientation. Barrels manufactured by Marlin have their name running lengthwise along the top of the barrel.

Barrel manufactured by Marlin

Barrel manufactured by subcontractor Brown-Lipe-Chapin for Inland.
B.I. is located on flat area on bottom of the barrel, the SG marking refers to the slide manufacturer.

Flaming Ordnance Bombs

As seen above, Underwood barrels have the flaming Ordnance bomb below the barrel date. Depending on the manufacturer, sometimes the flaming bomb is located on the right, left, or bottom of the barrel aft of the gas piston housing. Sometimes it's located on the integral gas piston housing. Not all barrels have the Ordnance bomb.

Ordnance bomb on an Underwood barrel with integral gas piston housing

Gas Piston Housing Markings

Gas piston housings occasionally have a subcontractor marking, most notably Inland barrels, or a prime contractor, like Rock-Ola.

Rock-Ola on right side of swaged gas piston housing
(sometimes on right instead)

I-I on front of swaged gas piston housing
(Inland subcontractor)

Sometimes subcontractor markings appear on the gas pistons used by Inland

Bottom of Barrel Flat

The barrel flat is the area along the bottom of the barrel between the gas piston housing and barrel threads. Sometimes the markings on the flat are a subcontractors mark, sometimes a proof mark, but more commonly are markings used in-house by the various workers and/or inspectors that made the barrel. The most prolific variety and quantity of markings on the flat are commonly found on barrels made by Inland and commonly referred to as Inland Hieroglyphics.

Inland Hieroglyphics - stamps used by employees/inspectors internally at Inland

Importer Markings

In October 1968 U.S. Congress passed the 1968 Gun Control Act. One of the provisions of this legislation required companies importing surplus U.S. military weapons, the Caliber .30 Carbines included, to place a marking on the weapon indicating who imported it. The same legislation created ATF, who was charged with enforcing this law, amongst many others. Funding ATF was not included in the legislation which inhibited enforcement of the law until circa 1971/1972. Since that time, all U.S. Caliber .30 Carbines imported into the United States from another country (who had received it under Lend-Lease or the Military Assistance Program) were legally required to have this import mark. The specific details the mark should include and location it should be placed varied until ATF finally issued guidelines for the importer markings.

Importer marked carbines are usually of lesser value as collectors (in general) don't want any markings that are not original U.S. manufacturer marks.

Importer markings may appear on the receiver but are more commonly found on the barrel. Some of these markings spell out the name and location of the importer, some are abbreviations. Following is a list of known markings of importers that may appear on the U.S. Caliber .30 Carbine barrels.

NOTE: This information is not considered complete, pertains only to the U.S. Caliber .30 Carbines, and does not include importer markings found elsewhere. This chart is only those known to appear on the barrel.

Importer Markings found on .30 Caliber Carbines Imported into the USA by Commmercial Companies after 1968

Company LocationImport MarkLocation on barrelOrigination
Arlington OrdnanceArlington, VA ARL ORD ARLINGTON VA bottom of barrel between band and front sight, illegibleSouth Korea
Armex InternationalBroderick, CAIA-CO. SAC. CA.bottom of barrel between band and front sightsee Pacific International (below)
Blue Sky ProductionsArlington, VA BLUE SKY/ARLINGTON, VA.left side of barrel between band and front sightSouth Korea
Century Arms, Inc.St. Albans, VT
Georgia, VT
bottom of barrel between band and front sight
bottom of barrel between band and front sight
no further info known
right side of barrel between band and front sight
DavidsonsGreensboro, NCDAVIDSONS GREENSBORO N.C.right side of barrel between band and front sightunknown
Exel ArmsGardner, MAEXEL/GARDNER, MA.right side of barrel between band and front sightunknown
Federal OrdnanceSo. El Monte, CAFEDERAL ORDNANCE INC
left side of receiverPhilippines 1986
GFCC Corp.Sacramento, CAGFCC CORP SACright side of receiver at end of slide channelIsrael
Inter-American Import Co.Sacramento, CAIA-CO. SAC. CA.right side of receiver at end of slide channelsee Pacific International (below)
InterarmsAlexandria, VAINTERARMS ALEX. VA.
right side of barrel just forward of receiver
on barrel between band and front sight
bottom of barrel behind front sightAustria
Navy ArmsRidgefield, NJN.A. Co.
left side of barrel forward of bandNorway & ?
New Helvetia Trade GroupSacramento, CANHM CO SAC CAbottom of barrel forward of bayonet lugIsrael + ?
Oyster Bay IndustriesOyster Bay, NYOBI


bottom of trigger housing

top of barrel 1.5" forward of gas piston housing, top of letters towards muzzle

P.R. China
(provided by
North Korea)
Pacific InternationalSacramento, CAIA-CO. SAC. CA.bottom of barrel between band and front sight1984-85 7000+ from P.R. China
1984-85 4000 from Israel
SAMCOMiami, FLSAMCO MIA FLbottom of barrel between band and front sightBrazil
Springfield SportersPenn Run, PASPR SPTR PN RN PAon barrel between band and front sightBrazil

Century Arms International - Georgia, Vermont

Barrel Characteristics

Gas Chambers

Gas chambers were manufactured by one of two methods. The earlier method used an integral gas chamber with the barrel and gas chamber machined from one piece of steel. Several manufacturers came up with an alternate method utilizing a gas cylinder that was press fitted (swaged) over the barrel, then drilled for the gas port. Ordnance approved the new method, while retaining the old method as also acceptable.

Integral Gas Cylinder (top) - Swaged Gas Cylinder (bottom)

Cut-a-way showing Swaged Gas Cylinder pressed onto barrel and gas port drilled through gas cylinder and barrel

Muzzle & Front Sight Area

The end of the barrels were cut to a slightly smaller diameter to accommodate the front sight. This cut was approximately 1.5" in length and could vary slightly depending on the manufacturer.

An oval keyway running lengthwise for the length of the front sight was cut into the top of this area. The key engaged the front sight pin to hold the front sight in place. Manufacturers assembling the carbines often staked the front sight at the rear for additional strength in holding the sight in place (see above picture under manufacturer markings). The manner of staking and the location differed somewhat from one manufacturer to the next.

The crown at the front of the barrel is the area immediately surrounding the bore that can effect accuracy if damaged. The crown differed depending on the manufacturer. Barrels serviced by Ordnance personnel occasionally have a counter bore into the chamber to correct damage to the crown.

Barrel Skirts

The first GI carbine barrels had what was/is called a "long skirt". This is an extension at the breach end of the barrel that surrounds the chamber from approximately the 10 o'clock position, downward and around to approximately the 3 o'clock position. The purpose of the skirt is to deflect the cartridges exiting the magazine into the barrel chamber. The decision was made by U.S. Ordnance the long skirt was not really necessary, they approved a "short skirt" which starts at about the 10 o'clock position, running downwards to approximately the 7 o'clock position.

Long Skirt (left) - Short Skirt (right)

Most barrel manufacturers changed to the short skirt. Some of the barrels with the long skirt were modified to a shortened version. Some retained the longer skirt. For civilian use, either skirt will function satisfactory unless the skirt is damaged in some manner.

Barrel Threads & Receiver Alignment

The threads on the end of the .30 Caliber Carbine barrel are timed to align with the threads in the front of the receiver so when the barrel is tightened onto the receiver the slide grooves in both the receiver and barrel line up properly. This also aligns the barrel skirt and gas piston properly. Barrels and receivers manufactured under contract to U.S. Army Ordnance have what is referred to as a witness mark to facilitate quick alignment of the barrel to the receiver.

Witness marks (alignment marks) on bottom of barrel and front of receiver.

If these marks do not line up, do not fire the carbine. Take it to a gunsmith or qualified armorer with the right tools and experience to align the marks and inspect the barrel and receiver.

Barrel Machining Marks

Some barrels were machined smooth, with no texture. Some barrels were machined with concentric circles around the barrel. Often the concentric circles have worn down. These differences are cosmetic only and have nothing to do with anything other than the tools used to machine the outside of the barrel.

Machined smooth

Machined with concentric circles

Bore wear is measured using a bore gauge ($20-$30). Accuracy is effected by many different things
but it is generally accepted the tighter the bore is to original dimensions, the more accurate it should be.

You may see owners measure the bore by placing the bullet end of a cartridge into the muzzle. This is a simple method
to check the wear to the lands and grooves. This should be done with a 30-06 cartridge instead of a .30 Caliber Carbine
cartridge as the shape of the round nose carbine bullet does not give an accurate assessment.

Where and Who to turn to for More Information and Further Assistance

I wish I could help everyone, but with over 6 million U.S. Carbines and almost 1 million post war commercial carbines one person can't handle all the requests for assistance. However, there are a number of resources available that can answer any question you might have, including groups of knowledgeable collectors and shooters on discussion forums. The internet is ripe with experts on almost every topic, so you would be wise to get opinions from more than just one person.

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