Commercial Barrel ID - Gas Chambers

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   The focus of this post is limited to the gas piston chambers along with the barrel design where they were attached. Most commercial carbine manufacturers did something unique that helps identify their barrels.

Other areas of these barrels sometimes have additional uniqueness but this post is about gas piston chambers.

The Barrel Manufacturers

There have only been a few commercial .30 cal. carbine barrel manufacturers over the years. Only one in the 1960's thru the 1980's. There have been some slight differences so their gas piston areas are shown with the commercial carbine manufacturers who have used them.

Small Arms Manufacturing, now Shaw Custom Barrels (1960's-1980's)
    Bridgeville, PA
Barrels were sold without a gas piston cylinder/housing. Buyers had to, and did, come up with their own. Each commercial carbine manufacturer that used these came up with their own unique design and/or method of attaching them to the barrel. Examples can be found below with Alpine, Bullseye, H&S, Iver Johnson, Millville Ordnance, National Ordnance, Plainfield, Rowen Becker and Universal Firearms

Criterion Barrels (since 1999)
    Germantown, WI
Swaged gas piston cylinders. Examples can be found below with Fulton Armory.

Green Mountain Rifle Barrel Company (since 1994)
    Conway, NH
Swaged gas piston cylinders. Examples can be found below with IAI, Auto Ordnance, and Inland Mfg,

Demilled Carbine Barrels with cut-down 1903A3 Barrels or other Inserts

Over time some carbine manufacturers chose to piece together their own barrels using the rear half of demilled GI carbine barrels into which they inserted a cut down 1903A3 barrel or other barrel. The GI swaged gas piston cylinder from the demilled carbine was usually used.

----------------------------------------------------------------------------------------------------------------------------------------------------------------GI Carbine Barrel Gas Piston Cylinders (for reference)

Top: Machined integral to barrel
Bottom: Separate piece swaged on

----------------------------------------------------------------------------------------------------------------------------------------------------------------The Commercial Carbine Manufacturers

ALM
    see IAI

AMAC  - unk barrel source (Iver Johnson 1986 & later)

Alpine - Small Arms Mfg

AMPCO
    receiver only

Armscorp
    receiver only

Auto Ordnance - Green Mountain

Bullseye - Small Arms Mfg

Ermas Mfg - 1903A3 inserts into demilled GI

Fed Ord - unk source but barrels are inserts into demilled GI rear half

Firearms International
    see IAI

Fulton Armory - Criterion

Global Arms
    see Millville Ordnance

H&S - Small Arms Mfg

Howa - made their own
Carbines made for Thailand

Howa sportering carbine

Inland Mfg - Green Mountain

IAI - Green Mountain

Iver Johnson - Small Arms Mfg
NJ & AR thru 1985

1986-end of production - barrel source unk

Johnson Arms
    see Plainfield

Liberty Armory
    see IAI

Mannlicher Sporting
    receiver only   

Millville Ordnance (MOCO) - Small Arms Mfg

National Ordnance - Small Arms Mfg

NATO
    see Plainfield

Plainfield - Small Arms Mfg

Rock Island Armory
    unknown which barrels they used

Rockola by James River Armory
    see Fulton Armory

Rowen Becker - Small Arms Mfg & 1903A3 inserts into demilled GI
Inserts

Small Arms Mfg

Springfield Armory
    barrel source unknown, most were receivers only but a few were sold with barrels

Texas Armament
    no barrels, receiver only

Universal Firearms - Small Arms Mfg

Top: Single recoil spring
Bottom: Hybrid twin recoil spring

Williams Gunsight
    see Plainfield

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sleeplessnashadow Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: Nov 09 2015 Location: SoCal Status: Offline Points: 1025	Post Options Post Reply Quote sleeplessnashadow Report Post Thanks(2) Quote Reply Topic: Commercial Barrel ID - Gas Chambers Posted: Jul 15 2022 at 2:26am
	The focus of this post is limited to the gas piston chambers along with the barrel design where they were attached. Most commercial carbine manufacturers did something unique that helps identify their barrels. Other areas of these barrels sometimes have additional uniqueness but this post is about gas piston chambers. The Barrel Manufacturers There have only been a few commercial .30 cal. carbine barrel manufacturers over the years. Only one in the 1960's thru the 1980's. There have been some slight differences so their gas piston areas are shown with the commercial carbine manufacturers who have used them. Small Arms Manufacturing, now Shaw Custom Barrels (1960's-1980's) Bridgeville, PA Barrels were sold without a gas piston cylinder/housing. Buyers had to, and did, come up with their own. Each commercial carbine manufacturer that used these came up with their own unique design and/or method of attaching them to the barrel. Examples can be found below with Alpine, Bullseye, H&S, Iver Johnson, Millville Ordnance, National Ordnance, Plainfield, Rowen Becker and Universal Firearms Criterion Barrels (since 1999) Germantown, WI Swaged gas piston cylinders. Examples can be found below with Fulton Armory. Green Mountain Rifle Barrel Company (since 1994) Conway, NH Swaged gas piston cylinders. Examples can be found below with IAI, Auto Ordnance, and Inland Mfg, Demilled Carbine Barrels with cut-down 1903A3 Barrels or other Inserts Over time some carbine manufacturers chose to piece together their own barrels using the rear half of demilled GI carbine barrels into which they inserted a cut down 1903A3 barrel or other barrel. The GI swaged gas piston cylinder from the demilled carbine was usually used. ----------------------------------------------------------------------------------------------------------------------------------------------------------------GI Carbine Barrel Gas Piston Cylinders (for reference) Top: Machined integral to barrel Bottom: Separate piece swaged on ----------------------------------------------------------------------------------------------------------------------------------------------------------------The Commercial Carbine Manufacturers ALM see IAI AMAC - unk barrel source (Iver Johnson 1986 & later) Alpine - Small Arms Mfg AMPCO receiver only Armscorp receiver only Auto Ordnance - Green Mountain Bullseye - Small Arms Mfg Ermas Mfg - 1903A3 inserts into demilled GI Fed Ord - unk source but barrels are inserts into demilled GI rear half Firearms International see IAI Fulton Armory - Criterion Global Arms see Millville Ordnance H&S - Small Arms Mfg Howa - made their own Carbines made for Thailand Howa sportering carbine Inland Mfg - Green Mountain IAI - Green Mountain Iver Johnson - Small Arms Mfg NJ & AR thru 1985 1986-end of production - barrel source unk Johnson Arms see Plainfield Liberty Armory see IAI Mannlicher Sporting receiver only Millville Ordnance (MOCO) - Small Arms Mfg National Ordnance - Small Arms Mfg NATO see Plainfield Plainfield - Small Arms Mfg Rock Island Armory unknown which barrels they used Rockola by James River Armory see Fulton Armory Rowen Becker - Small Arms Mfg & 1903A3 inserts into demilled GI Inserts Small Arms Mfg Springfield Armory barrel source unknown, most were receivers only but a few were sold with barrels Texas Armament no barrels, receiver only Universal Firearms - Small Arms Mfg Top: Single recoil spring Bottom: Hybrid twin recoil spring Williams Gunsight see Plainfield