Iver Johnson Arms

Post WWII Commercially Manufactured M1 Carbines (U.S.A.)

Iver Johnson Arms

Middlesex, NJ
Jacksonville, AR
Hardwick, VT


Section ISection IISection IIISection IVSection VSection VI
Iver Johnson Arms
Models Serial Numbers
Dates of Manufacture
Parts Brochures, Price Lists,
Fliers & Manuals


Section V



Every part on every gun has a lifespan. The failure of a part on a used gun manufactured between 1978 and 1992 cannot be directly attributed to the original manufacturer. M1 Carbines purchased as a used gun, regardless of who made it, should be safety inspected by a competent gunsmith before firing. The design of many semi-automatic rifles, M1 Carbines included, warrants it.

This website is not affiliated in any manner whatsoever with Iver Johnson's Arms or any other carbine or part manufacturer. The information provided here is for historical interests only.

Compatibility & Replacement Parts

With a few exceptions on their Enforcer pistols and 9mm Carbines, all of the parts used by Iver Johnson's Arms on their carbines are 100% interchangeable with surplus GI carbine parts and after market parts made to GI dimensions. If you need a replacement part it does not need to have been made by Iver Johnson. Sources for parts may be found on the Links page of this website.

The parts for the Enforcer pistols and 9mm Carbines that are not interchangeable with other carbine parts are addressed on the pages devoted to those models.

The parts used by Iver Johnson's Arms are presented within their respective groups as opposed to alphabetically.

Barrel GroupReceiver GroupTrigger Housing GroupStock Group
   Front Sight
   Barrel Band
   Bolt Group
   Rear Sight
   Trigger Housing
    All Internal Parts
    Recoil Plate

Barrel Group


The barrels initially use by Iver Johnson in New Jersey, were a continuation of those used by Plainfield Machine in the 1970's. The bore had 6 lands and grooves. The gas piston housing was inset into the bottom of the barrel and brazed in place. The barrel area forward of the gas piston housing where the barrel dimensions were reduced to the rounded forend had four distinct 45 degree corners.

Gas Piston Housing inset into barrel and brazed in place

Four 45 degree angle cuts leading to the reduction in barrel dimensions to the round barrel forend.

At some point after the company was moved to Jacksonville, AR the design of the barrel was changed. The barrel was changed to 4 lands and grooves. The rear half of the barrel was machined separate from the rounded forend. The rounded forend extended into the rear half of the barrel and all the way to the breach. The chamber was then reamed for the .30 caliber carbine cartridge. The gas piston housing was a separate piece that was swaged (compressed) into place with the gas hole then drilled through the bottom of the gas piston housing and into the barrel. This swaged gas piston cylinder was a variation of that used on many M1 Carbine barrels manufactured during and after WWII for the GI carbines.

Two piece barrel design with rounded section of barrel lengthened and inserted into rear half all the way to the breach.

A few of the Gas Piston Housings swaged in place were also pinned in place to secure them.

Examination of the breach reveals the rounded barrel inserted inside the outer rear half of the barrel.

Front Sight

Front Sights were milled steel throughout production. They were held in place using a keyed slot in the barrel, a cut for the upper half of the key in the front sight, and a roll pin (tension pin) to secure the Front Sight to the key and barrel. This is the design used throughout production for all front sights used during the production of the M1 and M2 Carbines manufactured during WWII.

Unlike their GI counterparts, the front sights used by Plainfield Machine followed by Iver Johnson's Arms in New Jersey were mounted at the rear of the turned down area on the front of the barrel that was designed to accommodate the Front Sight. This makes these barrels easy to identify as barrels having been used by Plainfield Machine, their predecessors Millville Ordnance and H&S, and their buyer, Iver Johnson's Arms. The downside of this Front Sight placement is it interferes with the use of front sight removal tools. While the roll pin (tension pin) is a very secure method of holding the front sight in place, roll pins can become deformed and/or rendered useless if removed and replaced using punches other than those designed specifically for roll pins. None of this is an issue if there is no need to replace the barrel band or Front Sight.

Note the placement of the Front Sight at the rear of the
turned down part of the barrel designed to accommodate the Front Sight.

The location of the placement of the Front Sight changed after the company was taken over by AMAC. The Front Sight was moved to the GI standard position of approximately midway along the turned down forend of the barrel.

Barrel Band

From 1978 through 1986 the standard barrel band used by Iver Johnson's Arms was a commercial equivalent to the GI barrel bands that preceded those with the bayonet lug. U.S. Army Ordnance had determined this design was superior to the thin bands initially used on GI carbines from beginning of production and into 1944.

After the assets of Universal Firearms were replaced from Florida to the Iver Johnson facility in Jacksonville, AR the barrel bands that had been manufactured by Universal appear on some of the Iver Johnson carbines manufactured 1985-1986. The Iver Johnson 9mm Parabellum model used these barrel bands exclusively (as well as the Universal Firearms handguard and receiver).

Universal Firearms Barrel Band

After Iver Johnson became a division of AMAC in 1987 the use of a commercially manufactured barrel band with a bayonet lug became standard.

Barrel Band used by AMAC 1987-1992


The slides used by Iver Johnson's Arms were made by casting and were modeled after the last slide of the GI carbines, which was used on both the GI M1 and M2 Carbines.

Note the casting mold mark running lengthwise down the center of the right side of the slide.


The gas piston, gas piston nut, operating spring, operating spring guide, slide stop, slide stop spring and other parts are interchangeable with their GI counterparts.

Receiver Group

Receivers and their markings are covered in detail in Section IV: Receivers & Markings.


Bolts manufactured for use with the Iver Johnson carbines were investment cast round bolts throughout production. The bolt design and all parts within the bolt are compatible with their GI counterparts.

Round Bolt manufactured for use by Iver Johnson's Arms

After the assets of Universal Firearms were relocated from Florida to the Iver Johnson facility in Jacksonville, AR in 1984, bolts made from forged steel for use with the late Universal carbines were also often used for the Iver Johnson carbines. Universal Firearms had changed the design of their bolts and firing pins in the late 1960's. Bolts used in the early to mid 1960's, all Iver Johnson bolts, and all WWII GI bolts utilized two safety designs to prevent the firing pin from moving forward and striking a primer before the bolt had rotated and locked into place. One was the design of the rear of the bolt and face of the hammer. The other was a tang on the rear of the firing pin that engaged a slot machined in the rear of the receiver bridge across the bottom of the receiver.

Universal eliminated the tang on the firing pin and added a strong spring that prevented the firing pin from moving forward until it was struck by the bolt. The design of the rear of the bolt was retained to prevent the hammer from striking the firing pin until the bolt had rotated and locked. Some have argued this eliminated a safety mechanism, making the Universal design unsafe. On the other hand, the design of the GI bolt and all commercial bolts based on that design were subject to another safety hazard known as a "slam fire". The redesign implemented by Universal did rely solely on the design of the rear of the bolt and face of the hammer to prevent the hammer from striking the firing pin before the bolt rotated and locked, but eliminated the redundancy of this safety design duplicated by the firing pin tang and instead eliminated the possibility of a "slam fire".

M1 Carbine Bolt Group

Universal Firearms Bolt Group 1968 and later

Universal Firearms on left, GI design on right. Note the design of the rear of both bolts.

The redesigned bolt manufactured by Universal Firearms is compatible with other M1 Carbines, however, the GI bolt design was no longer compatible with the Universal carbines. For further information on the bolts used by Universal Firearms refer to the pages devoted to Universal Firearms.

Rear Sight

The rear sight used by Iver Johnson's Arms throughout production was a commercial version of the stamped steel adjustable sight used on the GI carbines towards the end of WWII and post war.

Trigger Housing Group

Iver Johnson's Arms of Middlesex, NJ inherited the trigger housings used by Plainfield Machine in the 1970's. These were aluminum castings with the outer dimensions of their GI counterparts. All internal parts were cast from steel. The Hammer Pin and Trigger Pin are specific to these trigger housings and not interchangeable with their GI counterparts.

Note the non-standard Hammer and Trigger Pins

As the inventory of the above Trigger Housing diminished, Iver Johnson switched to a cast metal Trigger Housing made to GI dimensions. All of the parts were interchangeable with their GI counterparts, the Hammer and Trigger Pins included. All parts were machined from steel investment castings.

Stock Group

The stocks for the Enforcer carbine are located on the page devoted to the Enforcer Model.

Standard M1 Carbine Stocks

Manufactured throughout production to GI standards.



Paratrooper Stocks

Originally designed and manufactured by Plainfield Machine for their Paratrooper Model, Iver Johnson's Arms continued production until about 1984. The stock was the only thing different from the other carbine models. Iver Johnson manufactured these in both walnut and hardwood.

A word of caution... these stocks are prone to cracking, sometimes severely, when fired from the shoulder with the stock in the extended position. The damage occurs where the extended metal stock is held in place by the wood, sometimes cracking lengthwise along the two side channels and sometimes includes a horizontal crack across the rear of the wood between the two.

Survival Stocks

The stocks for the Survival Model carbines were manufactured by Choate Machine and Tool in Bald Knob, AR under contract to Iver Johnson's Arms 1983-1984. The stocks were made using a Dupont patented high strength, abrasion and impact resistant thermoplastic reinforced with fiberglass that Dupont had trademarked as Zytel. These stocks are the most durable M1 Carbine stocks ever made with similar versions still available from Choate as of 2013.

Fixed Stock

Folding Stock with cheek piece



Handguards made of walnut and hardwood to match their stocks were common on a few models. More common was a ventilated metal handguard with a design and hole pattern inherited from Plainfield Machine. With the addition of the assets of Universal Firearms, beginning in 1985 Universal Firearms Ventilated Handguards were intermingled with Iver Johnson Ventilated Handguards and used through the end of production on Iver Johnson carbines.

Iver Johnson's Arms Ventilated Handguard
Oval holes with 12 in each row, upper rows offset forward. Same as Plainfield Machine Handguards.

Iver Johnson's Arms Enforcer Ventilated Handguard
Oval holes with 9 in each row, upper rows offset forward.

Universal Firearms Ventilated Handguard
Oval holes with 11 aligned vertically in top and bottom rows with 12 in the center row extending it out at either end.

Additional information on the Enforcer Handguards is available on the page devoted to the Enforcer Model.

Since 1960 several companies have manufactured ventilated metal handguards. After the demise of Iver Johnson in 1992 some companies have copied the Plainfield/Iver Johnson pattern, others have copied the Universal Firearms pattern.


With the acquisition of the Plainfield Machine M1 Carbine assets, Iver Johnson's Arms inherited the rubber butt pad used by Plainfield Machine. These were used on a few of the first Iver Johnson carbines but were quickly replaced by a metal buttplate with a pattern specific to Iver Johnson's Arms. With the acquisition of the assets of Universal Firearms, beginning in 1985 the buttplates designed by Universal Firearms were intermingled with the Iver Johnson buttplates and used through end of production of the Iver Johnson carbines.

Iver Johnson

Universal Firearms
Iver Johnson


Recoil Plates used by Iver Johnson's Arms were machined from cast steel. A few Recoil Plate Screws and Buttplate Screws inherited from Plainfield Machine were Phillips Head screws but were quickly replaced with screws with a standard single slot head. Recoil Plate Screws and Escutcheon Nuts used by Iver Johnson's Arms were threaded different than their GI counterparts. While the two can used on other M1 Carbines and their GI counterparts can be used on Iver Johnson carbines, the threads of the two made by Iver Johnson are a matched set and not interchangeable with their GI counterparts (threaded different).