The U.S. Caliber .30 Carbines
|The Basics Here|
|The U.S. Caliber .30 Carbines||The Carbine Manufacturers||The Barrel Manufacturers||Parts, Variations & Markings|
|Carbine Nomenclature||The Serial Numbers||The Stocks & Handguards||Post WWII Ordnance Operations|
|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:
Prime contractors who manufactured their own barrels
Prime contractors who did not manufacture their own barrels (total of approx. 1,243,463 M1's)
These companies were supplied with barrels manufactured by Inland, Winchester, Underwood, Rock-Ola, IBM and two
Manufacturers contracted for Barrels only
(on flat between chamber & gas cylinder)
|Barrels Manufactured for:||Inland Division|
General Motors Corporation
(top of barrel, aft of front sight)
|Barrels Manufactured for:||replacement barrels|
Herlo Engineering Corporation
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.
(on flat between chamber & gas cylinder)
(none accepted by government)
|Barrels Manufactured for:||replacement barrels|
Things you should know:
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.
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.
Saginaw S.G. Div.
proof was oval
with PW logo
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 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.
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
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.
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||Location||Import Mark||Location on barrel||Origination|
|Arlington Ordnance||Arlington, VA||ARL ORD ARLINGTON VA||bottom of barrel between band and front sight, illegible||South Korea|
|Armex International||Broderick, CA||IA-CO. SAC. CA.||bottom of barrel between band and front sight||see Pacific International (below)|
|Blue Sky Productions||Arlington, VA||BLUE SKY/ARLINGTON, VA.||left side of barrel between band and front sight||South Korea|
|Century Arms, Inc.||St. Albans, VT|
CENTURY ARMS INC. ST. ALBANS VT. |
CAI ST ALB VT
CIA ST ALBANS VT
C.A.I. 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
|Davidsons||Greensboro, NC||DAVIDSONS GREENSBORO N.C.||right side of barrel between band and front sight||unknown|
|Exel Arms||Gardner, MA||EXEL/GARDNER, MA.||right side of barrel between band and front sight||unknown|
|Federal Ordnance||So. El Monte, CA||FEDERAL ORDNANCE INC|
SO. EL MONTE, CA.
|left side of receiver||Philippines 1986|
|GFCC Corp.||Sacramento, CA||GFCC CORP SAC||right side of receiver at end of slide channel||Israel|
|Inter-American Import Co.||Sacramento, CA||IA-CO. SAC. CA.||right side of receiver at end of slide channel||see Pacific International (below)|
|Interarms||Alexandria, VA||INTERARMS ALEX. VA.|
INTERARMS ALEX VA
right side of barrel just forward of receiver|
on barrel between band and front sight
|INTRAC Arms||Knoxville, TN||INTRAC|
|bottom of barrel behind front sight||Austria|
|Navy Arms||Ridgefield, NJ||N.A. Co.|
|left side of barrel forward of band||Norway & ?|
|New Helvetia Trade Group||Sacramento, CA||NHM CO SAC CA||bottom of barrel forward of bayonet lug||Israel + ?|
|Oyster Bay Industries||Oyster Bay, NY||OBI|
OYSTER BAY IND
|bottom of trigger housing|
top of barrel 1.5" forward of gas piston housing, top of letters towards muzzle
|Pacific International||Sacramento, CA||IA-CO. SAC. CA.||bottom of barrel between band and front sight||1984-85 7000+ from P.R. China|
1984-85 4000 from Israel
|SAMCO||Miami, FL||SAMCO MIA FL||bottom of barrel between band and front sight||Brazil|
|Springfield Sporters||Penn Run, PA||SPR SPTR PN RN PA||on barrel between band and front sight||Brazil|
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.
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.
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.
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.
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 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.
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