U.S. .30 Caliber M1 Linked Ammunition Belts
By Charles Brown

The first mention of metallic linked .30 caliber ammunition in connection with the ground type Brownings that the author has encountered is a description of the color coding of ammunition crates in FM 23-45 Basic Field Manual Browning Machine Gun, Caliber .30, HB, M1919A4 Ground. This field manual, published in 1940, notes that linked ammunition is in “Special packing for Air Corps, and not for use in the Browning machine gun caliber.30 M1919A4.”

The WWII use of .30 Caliber M1 steel links was almost completely confined to ammunition loaded for use in naval aircraft until very late in the war when ammunition loaded in AP/API/APIT (armor piercing / armor piercing incendiary / armor piercing incendiary tracer) configuration began to be issued to armored and ground forces.. The author knows of one firsthand account that dates the introduction of M1 linked caliber .30 ammunition to the 69th Armored Field Artillery Battalion. This unit, which operated the M7 Motor Gun Carriage (self-propelled 105mm howitzers mounted on M3 tank chassis), began to sporadically receive linked caliber .30 ammo shortly after the commencement of Operation Dragoon, the invasion of Southern France, in August, 1944.

While linked ammunition in quantity did not appear in general use for ground units until about the early/mid 1950s, Ordnance actually began considering the development of some alternative to all fabric feed belts at least for aircraft shortly after the end of the of WWI.

In February 1931, Ordnance finally settled on the basic design that would remain virtually unchanged, despite a few hiccups, until the end of the service life of Caliber .30 Browning machine guns. The .30 caliber metallic links were designated M1 to conform to the naming convention in use at the time. This design was at the behest of the Army Air Corps, who's primary automatic weapon mounted on the aircraft of the day were the .30 caliber Browning Aircraft machine guns. What brought this about was the use of machine guns in open cockpit aircraft. As the belt emptied the free end was left to flap around in the slipstream striking the gunner or actually punching holes in the fabric skin of the aircraft. Empty belts that went overboard sometimes became tangled in control surfaces with predictable results. As aircraft performance increased the problems became worse. The first solution was various methods of rolling the empty portion of the belt up automatically or otherwise confining as it was emptied. With advances in aircraft armament such as machine guns installed in the wings and power driven turrets the fabric belt's days for aircraft use were numbered.

Feed belts of the M1 link type are often somewhat confusingly called "disintegrating link belts." The links do not disintegrate, the belt does. More properly stated, the links become disengaged from each other after the cartridge is extracted from the belt and are either pushed out the open side of the feed way or are directed into a chute that carries them to a bag or in the case of wing mounted weapons in WWII aircraft allowed the links to fall clear of the aircraft along with the empty cartridge case. The links, while considered combat expendable just like the fabric belts they can be and are reused, at least by recreational shooters. Rock Island Arsenal developed pilot production methods and was the sole producer of this seemingly simple and cheaply made piece of sheet metal until just prior to WWII. Looks are often deceiving, especially in this case, as the links are neither simple nor cheaply made. The material that the links were fabricated from was carefully selected and the specifications were changed several times. Aluminum was an early choice as a weight saving measure, but it was considered to be a "critical" material in war time. Various steel alloys were considered. One alloy that was favored was rejected because it contained substantial amounts of manganese, another "critical" material.

The M1 Caliber .30 link was adopted as the standard until the Air Corps began to equip aircraft with power driven turrets having ammunition feed chutes. The Air Corps felt that M1 linked ammunition did not have sufficient flexibility and tended to jam in the feed chutes so RIA began to experiment with changes to the M1 design which led to the Ordnance Technical Committee meeting of January 16, 1941 Item 16396 which recommended the adoption of the more flexible M2 link as the standard link and the M1 links to limited standard status.

The Air Corps now had the links it needed, except for a couple of problems. The M2 link functioned fine in all the .30 caliber ground guns if fed in the standard manner i.e. double loop first, but did not work well in the linking machines and if fed into weapons backwards, that is with the single loop first the M2 Caliber .30 links caused stoppages, which were politely referred to as "causing the gun to cease to function."

Between the time of the tests of the M2 links conducted by the Air Corps and the Ordnance Committee's rather hasty action in declaring the M2 to be the Standard, the Air Corps had reached the conclusion that the .30 caliber round lacked sufficient power and range to be effective against modern aircraft. Their new operating policy would in the future use only .50 caliber weapons to arm its aircraft. Unfortunately they failed to promptly notify the Committee of this new state of affairs.

The Ordnance Technical Committee revisited the M1/M2 Caliber .30 link question in the meeting of May 1, 1941 as Item 16669. They promptly reversed course and recommended to the Chief of Ordnance that the M2 Caliber .30 link be declared obsolete, after just 5 months, and the M1 .30 Caliber link to be once again the Standard. While all this was going on the Committee on 4-10-41, as Item 16619, recommended that experiments with plastic links be continued by RIA. This never amounted to much because the plastics of the time did not have the requisite properties in temperature extremes. With the M1 Caliber .30 link again the standard and WWII just over the horizon three civilian manufacturers received contracts to supplement RIA’s link production, Jackes-Evans Co., Fort Pitt Bedding, later known as Ft. Pitt Manufacturing and General Aviation Equipment Co.

At various times during WWII there were about 30 different plants producing both .30 and .50 links. Some of the identification of the manufacturers like Crown Cork and Seal, which used a very fitting symbol, a bulls-eye, or the Firestone Steel Atlanta, GA, Fall River, MA and Wyandotte, MI plants that used the stylized "F" in the Firestone trademarked name with an "S" on the shaft and very small characters to indicate the plant and machine or die would be very hard to read. Firestone's Memphis plant omitted the "S" on the shaft of the F likely because it was not a Firestone Steel plant. The symbols for American Can Company, Owens-Illinois and National Stamping Company also appeared on the M1 ammunition boxes they produced. Owens-Illinois' symbol changed after January, 1943 to an I inside the O. M1 links were also produced in Canada by the Dominion Arsenal, Quebec; the author has seen samples marked DAQ, and there were possibly other Canadian manufacturers.

Ordnance required that the links be identified both to production plant and the die/machine that produced the individual link. This allowed inspectors to very quickly track down any defective links being produced, hopefully, before they got out of the plant. The Army converted to the exclusive use of the M1 steel link with production of replacement ammunition for the huge stock of WWII functional lot loaded fabric belted ammunition consumed during the Korean War. The increasing use of steel linked ammunition in ground type Brownings during the Korean War brought up several new problems, the most serious for the operator was stoppages caused by the links jamming against the fixed plate of the cover hold open device.

Ordnance solved this problem in 1951 by redesigning the short round stop by adding a finger to the right end of the stop. This finger extended over the edge of the fixed plate of the cover hold open device to deflect the empty links. By September, 1953 Modification Work Order MWO ORD A6-W14 had been issued to install the improved short round stop on all air cooled .30 BMG weapons in the field.

John Browning’s design of the Model of 1917 water cooled MG, the parent of all the .30 caliber air cooled Brownings, was based on an all fabric feed belt, which he felt was the best feed system. Increasing use of linked ammunition led to unanticipated wear on the top of the trunnion. The floor of the M1919 feed way, which was also the very thin top of the trunnion block where the rear barrel bearing passed through, began to show grooving from the friction wear of the links passing over the floor of the feed way. This problem was solved by removing the trunnion and chrome plating the surface to build it up to original dimensions. Additionally the chrome plating was much harder than the original surface and provided superior wear resistance. Recreational shooters use a thin stainless steel “trunnion protector” that snaps over the floor of the feed way to prevent wear on the trunnion itself.

With the WWII ammunition supply shrinking from state side training use or as military assistance items given or sold to "friendly" nations, the fabric ammunition belt, at least in U.S. service, began its decline into obscurity. Throughout WWII RIA produced M1 .30 caliber links and with the end of the war production ceased. With the onset of the Korean War in July, 1950 link production at RIA resumed and by June 1954 RIA had produced just over 29 million M1.30 caliber links when production was once again halted.

As with the fabric belts some method of linking ammunition in the field was necessary. Several mentions are made in the Ordnance Committee Meeting minutes of efforts to modify the hand operated .30 caliber fabric belt loading machine to load ammunition into links. Because of the limited issue of linked ammunition to ground forces nothing was ever done with these experiments. The Ordnance Department did develop a much simpler and cheaper device, the M3 linker for .30 Caliber ammunition. The M3 linker and M8 Attachment which linked (or de-linked) 20 rounds at a time, the same number of rounds in each pasteboard ammunition carton and number of links in each cardboard box. The "Attachment, M8" is a plate that when placed in the linker along with linked ammunition de-links it. RIA produced about 25,000 of these manual linkers and plates during and just after the Korean War.

Post Korea large quantities of M1 links were produced by Wells Marine, Inc. and marked WM. M1 links both unused in the original cardboard carton and bulk left over from the de-linking and repackaging of millions of rounds of .30 Caliber M2 Ball machine gun ammunition sold by the Civilian Marksmanship Program and the de-militarizing of additional millions of linked rounds make up the bulk of links presently available to the public.

With the change over to 7.62x51 NATO ammunition and the concurrent adoption of the M60 GP machine gun in 1957, which used the M13 “push through” link, the .30 Caliber feed devices for the Browning machine gun, both fabric belts and steel links, began to fade into the distance.

This article first appeared in Small Arms Review SAW (July 2012)
and was posted online on June 1, 2012


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