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                                                                                                                                                                                          The M1919A6

 

The development and issue of the M1919A6 Caliber .30 Browning  light machine gun always reminds me of the old saying that a camel is a horse designed by committee. 

It looks like the small arms equivalent of a couple of kids building a dog house from scrap lumber.

The A6 was fathered by necessity and birthed by expediency. 

In early 1942 the U.S. Army Infantry Board began to think in terms of a weapon to replace the M1918A2 Browning Automatic Rifle as the squad base of fire. 

The BAR was accurate, reliable and generally well liked by the troops, however it had a few drawbacks.

It was expensive, difficult to manufacture, unable to provide sustained covering fire because of the limited magazine capacity of 20 rounds and overheating. 

The M1918A2 was the result of an “improvement” process applied to the M1918 version.

The improvements consisted of a barrel mounted bipod, redesigned flash hider, modifications to the trigger housing to provide guides for magazine insertion, a rear sighting system providing windage adjustment and removal of the selective fire option replacing it with two rates of full auto fire. 

Later in 1944 a barrel mounted carry handle was also developed along with a change to the design of the bipod legs.

The Infantry Board wanted a relatively light weight weapon that was rifle caliber and belt fed capable of some level of sustained fire and able to be deployed by one man. 

The Infantry automatic weapon work horse was the M1919A4 .30 caliber air cooled Browning mounted on the M2 tripod.   Weapons Platoons were also equipped with M1917A1 water cooled Brownings. 

The M1917A1 had almost unlimited sustained fire capabilities provided you had an adequate ammunition and water supply but the M1917A1 mounted on it’s like designated tripod weighed in at nearly 100 lbs.  

If deployed at all it was relegated to static/defensive positions.

The M1919A4 needed two men to deploy, the Gunner carrying the tripod and the Assistant Gunner carrying the A4.  The tripod/A4 combination weighed in at 48 lbs and usually was separated into two pieces to change the weapon’s position.

The Infantry Board was familiar with the German MG 34 and MG 42 weapons which featured a butt stock and a bipod mounted on the weapon, they could also be mounted on a tripod if the need arose.

This appeared to be the style of weapon best suited to the perceived task.

Ordnance wanted to purpose build a weapon to serve the Infantry’s needs.  However the system in use at the time to solicit designs, develop new weapons then test, field trial, and mass produce took years. 

The Infantry Board, well aware of the time required to approve new weapons, needed something to satisfy their needs yesterday not years down the road.

In hindsight the Board hit the nail on the head regarding the long lead time to production of a new weapon. 

The M1919A4/A6 was replaced by the M60 GP machine gun in 1957. 

Much wrangling back and forth ensued with the Infantry suggesting that the M1919A4 currently in production could be modified at little cost using non critical materials to satisfy their immediate needs and some new weapon could be developed at a later date.

By early 1943 Ordnance agreed to develop a kit of accessories to be furnished to adopt the M1919A4 to the configuration that the Infantry desired.

During  development and testing of the new accessory kit Ordnance discovered that this was not going to be a stroll in the park and decided to purpose build and name the modified weapon M1919A6 and declare it a Substitute Standard, Major Item number 51-125.  

One of the design shortfalls of the M1919A4 was the fact that the barrel had to be changed from the rear and required removing the back plate, bolt, lock frame, barrel and barrel extension in short you had to field strip the weapon.

The German MG 34 and MG 42 had a much simpler and faster method of barrel change where the receiver pivoted to expose the chamber end of the barrel.

Ordnance had been experimenting with modifications to the A4 to provide a quicker method of barrel change. 

These experiments were based on various designs for changing the barrel from the front including a barrel support similar to the Caliber .50 Brownings. 

The A6 development looked like a good time to try for a  different style front changeable barrel.

 

Here’s a picture of an early experiment with a front change barrel assembly that looks remarkably like the Caliber 50 air cooled Brownings.

One of the problems that surfaced with the development of the air cooled M1919 Tank Gun the parent of the M1919A4, which were based the M1917 water cooled design was the need for a heavier barrel to dissipate the heat generated by the lack of water cooling. 

The Tank Guns had 18 inch barrels that weighed about 5.5 lbs versus the M1917 barrels weight of 3 lbs. 

The M1917 was a purely recoil operated weapon. 

Since the recoil energy of the cartridge remained the same and the weight of the recoiling parts increased additional energy to provide reliable operation of the weapon had to come from somewhere. 

John Browning solved the immediate problem by placing a “muzzle attachment” at the front of barrel jacket that also served as a front barrel support bearing and a “muzzle attachment plug” containing a .872 hole.

Later this arrangement became known as a “booster”

During the very short time that the projectile entered the booster chamber and exited through a much smaller orifice expanding gas pressure resulting from the burning of the propellant exerted force on the front of the barrel providing additional rearward thrust or “boost” which compensated for the heavier recoiling parts.

Technically speaking the M1919’s are recoil operated/gas assisted

When the M1919A4 was developed, it was decided to increase the barrel length to 24 inches to provide higher muzzle velocity and increased range. 

The change to the 24 inch barrel increased the weight of the barrel to 7.5 lbs and required changes in the “booster” system, basically making the orifice smaller which added additional rearward thrust.

Apparently during the initial design of the A6 the subject of front changing barrels resurfaced and someone came up with the idea that the boost feature could be eliminated by decreasing the weight of the recoiling parts.

Eliminating the booster and shortening the barrel jacket so the end of the barrel would be accessible would allow the barrel to be removed from the front and replaced. 

The only practical way to do this was to make the barrel lighter so a barrel with a slimmer profile and wrench flats on the end was designed.

This page from TM 9-206, courtesy of the 90th Infantry Division Association, printed in September,1943 just about the time M1919A6 made its battlefield debut, explains  how to change the barrel from the front. 

While no mention of the M6 combination wrench is made, the opening with the rounded ends that is used to turn the booster plug and booster bearing wrench also fits the A6 barrel's wrench flats. 

The operators of the weapon still had the option of changing the barrel from the rear if they wished.

Conventional wisdom has always held that the reason for lighter A6 barrel was to reduce the overall weight of the weapon which it did.

However, the real reason for a lighter barrel was that it would reduce the weight of the recoiling parts, the reason for having a gas assist booster in the first place.   

The shortened barrel jacket and lack of a booster plug on the A6 resulted in the muzzle with the wrench flats protruding from the end of the front barrel bearing. 

Since the front barrel bearing was bored straight through at 1.254 the barrel of the A6 could be changed from the front with or without the use of M6 combination wrench.

Some writers believe that the protruding wrench flats on the barrel were an attempt to make it easier to set the head space, however, there were already methods to adjust head space that required only the use of a cartridge.

The first M1919A6’s were committed to combat in the Italian Campaign around Salerno in the fall of 1943 and later at Anzio in January 1944. These A6’s had the original front barrel bearing having no gas assist booster.

The decision to reduce the barrel mass to have a front changeable barrel was probably not a good one.  The M1919A4 with its 7.5 lb barrel was already marginal on overheating during sustained fire.   Reducing the barrel mass did not make this situation any better

The Saginaw Steering Gear Division of General Motors, the premier quality, low cost and high production manufacturer and, after July, 1943 the only producer of the M1919A4, was selected to be the producer/developer of the new weapon.

Saginaw got busy and fabricated  some new parts cast using an alloy developed by Saginaw Malleable Iron, one of their subsidiary companies.  This alloy, a perlitic malleable iron, called ArmaSteel, had been developed pre-war to cast certain automotive parts that were difficult to machine.

Saginaw had already used ArmaSteel to fabricate some M1919A4 parts with great success.

The new M1919A6 parts were a one piece front barrel bearing having no booster feature and the head section of the bipod which slipped over the bearing and was retained by a snap ring. 

The bipod head was designed to mount the same adjustable legs used on the M1918A2 BAR. 

The new front barrel bearing had to be longer than the original to accommodate the bipod head resulting in the need for a shorter barrel jacket.

A sheet metal butt stock and a rather flimsy sheet metal and plastic carry handle that slipped over the barrel jacket was also standardized.

A review of the Ordnance Department drawings of A6 specific parts shows a common original date on the drawings of 7-23-43. 

I take this to be a convenient earliest date to cite for beginning of production.

This cut from SNL (Standard Nomenclature List) A-6 dated September 1943 is the first SNL illustration of a production M1919A6. 

The adjustable BAR legs are supplemented by two small fixed rests just below the leg attachment to the bipod head for use when the legs were folded in the up position.  The early style carry handle is free to slide up and down the jacket and often did at the most inopportune times. 

The length adjustment thumb screws for the legs are located  at the bottom of the fixed leg just above the feet of the sliding leg when at the shortest position.

This adjustment feature would be changed in 1944 along with a new carry handle similar to the M1918A2 BAR carry handle introduced in 1945.

Other than the added parts the weapon remains a M1919A4.  And just like the A4, with the addition of a pintle the A6 could be mounted on any tripod that would accept the A4.

M1 metal links on the left, fabric 250 round belt on the right.  The cartridges with the red tips are the tracer rounds.

Like all the other M1919’s the A6 could use either ammunition supplied in fabric belts or metallic link belts.

Typically during WWII infantry machine gun ammunition was furnished in “Functional Lot” form; for machine guns the cartridges were belted or linked in 250 round units and packed in an expendable metal container, the M1 ammunition box shown above, four containers in a wire bound wooden crate, ready for use. 

Commonly, Infantry units used the ratio of 4 Ball to 1 tracer.

In order to conserve steel for strategic uses fabric belts were used almost exclusively for ground units. 

My wife’s Uncle a member of the 69th Armored Field Artillery Battalion stated they would occasionally receive linked ammo after the invasion of Southern France in August, 1944.    

  

 

 

This cut also from the September 1943 SNL shows barrel group parts from both the A6, the upper part of the illustration, and the A4 and A5 in the lower. 

While the barrels are the same length 24 inches the C93962 jacket for the A6 is 16.5 inches long vs. the A4 jacket at 19 inches in length.  The length difference is made up by the longer front barrel bearing required to mount the A6’s bipod head.

 

Another cut from TM 9-206 showing details of the early A6 specific parts including an unusual looking top cover latch which we have not seen before.

This view clearly shows the lack of a booster and the protruding muzzle with the wrench flats.

Even when it was discovered after the Italian deployment  that the A6 required a gas assist booster to operate reliably and the cap style booster and a newly designed front barrel bearing were adopted, by simply removing the booster cap the operator would have access to the flats on the end of the muzzle preserving the front barrel changing capability.

Author's photo courtesy of the RIA Museum.

While some A6’s were purpose built and can be identified by the designation M1919A6 stamped on the right side plate of the casing, some weapons were rebuilt into the A6 configuration from other models such as the M1919A4 Fixed weapon used on early tanks and the M1919A5 designed primarily for the M3A1 Stuart light tank.  These rebuilt weapons can be identified by over strikes on the side plate model designations.

The photo of the A6 above shows that it has lived several lives. 

Originally built by RIA as a M1919A4 in about September of 1941 it was converted by RIA to M1919A5 (Note the 4 holes for the retracting bar guides and the first model designation overstrike) configuration  also note the faint "FK" (Frank Krack) to the right of the "U.S. INSP". 

The weapon was not remarked on conversion to M1919A5 because it was done at the same facility with the same Chief of Small Arms Inspection as already marked and Ordnance directives did not require remarking under these conditions.

However, this weapon was remarked near the top of the right side plate on conversion to M1919A6 with the RIA and "EB" (Elmer Bjerke) who succeeded Krack on January 6, 1947.   Mr. Bjerke remained the RIA Chief of Small Arms Inspection until his job was eliminated in 1958. 

According to Goldsmith Volume 1, 330 M1919A5's were converted to M1919A6's between 1955 and 1957.  The weapon pictured may be one of the weapons referred to.

All of the purpose built A6’s in the WWII era were produced by Saginaw Steering Gear in their Saginaw, MI plant. 

Rock Island Arsenal may have done some A6 conversion work to meet demands for these weapons during WWII.

 

This cut is from ORD 9 SNL A-6 dated April 1947 and shows the cap style booster and its companion front barrel bearing along with the early style clip to lock the cap to the bearing.  This style appeared sometime in the summer of 1944 apparently as a result of problems encountered in combat use during the Italian campaigns of 1943 and early 1944.

This arrangement required yet another and even shorter barrel jacket C7160455 which has an overall length of 15.9 inches.

Apparently the early A6, recoil only model lacking the gas assisted booster did not apply enough recoil force to the barrel for reliable operation.  

In addition the snap ring bipod retainer on the original design was only .048 inches thick and sometimes broke allowing the bipod to slide off the front of the weapon. 

The last style bipod retaining snap ring thickness was increased to .094 inches. 

The removable booster cap allowed easier cleaning than the one or two piece A4 boosters.

  

 

 

This cut also from the 1947 ORD 9 SNL A6 shows the late/post WWII configuration.

This illustration shows the “new” style adjustable legs adopted in July of 1944.  This style consisted of the same leg parts as the old but assembled them differently.   The length adjusting thumb screw is located just below the thumb screw used to hold the legs in the folded or extended position. 

The early style had the length adjusting thumb screw just above the foot where it was difficult to grasp and became jammed with mud.  This leg change also affected the M1918A2 BAR.

Also shown is the cap style booster and the early "U" shaped version of the clip that locked the cap to the bearing.  Later this clip was modified with a hinged arm to lock the clip in place.

Also present was a new style carry handle that appeared in April of 1945 that clamped to the barrel jacket and didn’t flop around like the cheesy original.  This handle is similar to the design of the BAR carry handle.

One problem that affected U.S. troops in the European Theater in WWII was the excessive, as measured by German standards, flash signature of our weapons.

Efforts began as early as 1943 to develop some sort of flash hider for the Browning .30 calibers many were tried, but only one design showed both promise and adaptability.  This style used a simple cone with an included angle of about 15 degrees.

The M6 flash hider replaced the booster/bearing on the M1919A4, the M7 replaced the booster cap on the M1919A6 and the M8 and a modified muzzle gland was developed for the M1917A1 water cooled machine gun.  While these were developed late in WWII, very few, if any, ever made it to the field.

 

 

This cut is from MWO ORD A6-W12 (Maintenance Work Order for Group A-6 weapons) dated July 1949.

A-6 Group weapons include all of the M1919 family of air cooled caliber .30 Brownings.

The purpose of this work order was to replace all of the cap style muzzle boosters and bearings on M1919A6 weapons with the .048 inch bipod retaining rings and the early style M7 flash hiders with the newly dimensioned booster chamber M7 flash hider.

This MWO only affected weapons in the field or weapons being reconditioned, not weapons in storage.

This would explain why few Korean War photos of A4’s or A6’s show flash hiders.

When the Korean War started Ordnance apparently issued weapons directly from storage without modifying them.

Apparently there will still issues with insufficient gas assist force because the latest design M7 flash hider  for the M1919A6  has a larger booster chamber.

Only about 44,000 M1919A6’s were produced during WWII.

 

Photo courtesy of the RIA Museum.

This is the final post Korean War version complete with M7 flash hider.  Note the left side view showing the rear sight base having only two attaching rivets and no milled cut or tapped holes for an optical sight base.

The left side plate shows the unused third rear sight base mounting hole.  The flash hider is equipped with the last style mounting clip with the swinging arm.

The right side plate shows the four holes for the retracting bar guides required on the M1919A5. 

The M1919A6 remained in active U.S. service through the introduction of the M60GP machine gun in 1957. 

Some units were still using the M1919A6 into the early stages of the Vietnam War and Army National Guard and Reserve units had them in their arms rooms into the mid 1960s.

In 1949 the  Rock Island Arsenal began to produce A6 components for rebuilding of existing A6's and the conversion of M1919A4's to A6's. 

These components included M7 flash hiders, front barrel bearings, carry handle assemblies, shoulder stocks, bipod heads and barrels.

In 1952 RIA began planning for the resumption of Caliber .30 Browning machine gun production this was likely to replace battle losses in the Korean War.

RIA hadn't produced a new .30 Caliber Browning Machine gun since 1944.

The History of the Manufacturing Plant of the Rock Island Arsenal 1 July 1953-30 June 1954 indicates that 7,200 new M1919A6's were produced along with rebuilding 587 A6's.

The RIA Historical Summary for the period of 1 July through 31 December 1955 lists the manufacture of 3 M1919A6's.  These are likely the last RIA purpose built A6's.

Total RIA production of purpose built M1919A6's in this period is somewhere around 9,000 weapons.  An exact count is complicated by missing records.

The Historical Summary for the period 1 July  through 31 December 1957 lists 432 M1919A6 rebuilt from M1919A4 Flexible models.

This is the last mention found so far of RIA's involvement with the M1919A6. 

On 12 July 1957 RIA transferred responsibility for small arms production and engineering support to the Springfield Armory now the site of the Springfield Armory National Historic Site.  

In addition to the Rock Island Arsenal's post Korean War A6 production Saco-Lowell Shops, Biddleford, ME, best known for building M37's, also produced purpose built M1919A6's, however, records concerning their production are sparse. 

Lake City Ammunition Plant was still loading Caliber .30 Ammunition as late as 1976.

As the M1919A4 and M1919A6 were being phased out of U.S. service a good number of them were transferred to the Israeli Defense Forces as military assistance items.

The IDF made a few modifications necessary to convert them to caliber 7.62X51 NATO and designed a new bipod as part of a kit containing a carry handle and sheet metal stock that could convert any M1919A4 into a sort-of A6.   

The IDF reverted to the "Kit" concept and used standard profile A4 barrels and converted some M1919A4's into a sort of A6 using either the M6 flash hider or a conventional booster/bearing. 

What they sacrificed in increased weight and loss of the front change barrel option they gained back in improvement in barrel heat dissipation and tactical flexibility.

The IDF produced sheet metal butt stock which is an exact copy of the USGI design however it is marked with Hebrew characters on the right side upper rear of the stock.

 The M1919A4 and the A6 wannabes soldiered on with the Israeli’s for quite some time. 

The IDF was still contracting fabric belt production in the Netherlands in 1976.

The IDF favored a 225 or 230 round fabric belt because it would fit more conveniently in the post Korean War M19A1 ammunition box which would also hold 250 rounds of linked 7.62X51 or U.S. caliber .30 ammunition.  

Author’s photo

The IDF designed and produced bipod offers a few improvements to the original design.

While it has fixed length legs the bipod is locked to the barrel jacket holes with a spring loaded pin, the knurled knob in the picture, and can be positioned anywhere on the barrel.  In addition the attachment to the jacket allows the operator to traverse about 20 degrees and to cant the weapon without picking up the bipod and repositioning it or skidding the feet.

Purists turn up their noses at the IDF bipod because it’s not USGI but, even though it’s a little heavier, it is more practical design for the operator.

 

Author’s photo

With the legs folded you can see the solid steel block that takes the place of the two sheet metal rests on the USGI bipod.

Most of the “parts kits” available on today’s market for conversion to semi-automatic versions of M1919A4/A6’s are Israeli vets and marked with IDF property marks.

The M1919A6 like most compromises left everybody a winner, or looser, depending on your point of view.

The infantry got a weapon sooner rather than much later, and Ordnance got to develop the M60GP machine gun.

Funny thing about the M60, there’s no middle ground; the users either loved it or hated it.

 

                                                            Credits: 

All Ordnance publications pictured or quoted:

Rock Island Arsenal Museum, Jodie Creen Wesemann

 

Infantry Weapons Of WWII, Bruce Canfield, Andrew Mowbray publishers

The Browning Machine Gun Volume 1, Dolf Goldsmith,

Collector Grade Publications

Hard Rain, Frank Iannamico, Moose Lake Publishers