A Brief History of .50 Browning Machine Gun Cartridge Development
by Keith Pagel
Very High Power Magazine
Fifty Caliber Shooters' Assn.
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(A head-to-head comparison of the .308 Winchester with the .50 BMG cartridge.)
| ||.50 BMG||.308 Win
|Cartridge metric designation:
||12.7 x 99
||7.62 x 51
|Initial date of development:
|Nominal projectile diameter:
|Listed Max Effective Range:
|Muzzle energy *:
||12,000 + ft-lbs
||2,400 + ft-lbs (2)
|Projectile weight *:
||665 grains (3)
||147 grains (3)
|Cartridge total weight *:
||1760 grains (3)
||390 grains (3)
|Muzzle velocity *:
||2900 fps (3)
||2750 fps (3)
|Max chamber pressure:
||55,000 psi (3)
||50,000 psi (3)
|Ballistic Coefficient *:
|Case nominal OAL:
||2.015 inch (2)
|Cartridge nominal OAL:
||5.450 inch (3)
||2.800 inch (3)
* Figures vary widely depending on particular loading. Numbers cited are typical, current, US military issue Ball.
Initial Development :
Tradition has it that the cartridge that was to become the .50 BMG we know today, was initiated at the personal request of General John (Blackjack) Pershing. This request for a heavy machine gun cartridge came in light of American experiences with the large-caliber weapons employed by the European nations during WW1. The request, in April 1918, for a weapon with an effective range of 6,000 meters and a muzzle velocity of 2600 fps was contracted to the Winchester Repeating Arms Company. The proposed cartridge was to have both machine gun and anti-tank capabilities.(1)
Later that same month, Winchester began the fabrication of test cartridges to obtain ballistic data. Initially they used 16-gauge, brass shotshells, necked down to accept commercial 500-grain lead 45-70 projectiles. Propellant charges used varied from 120-150 grains, developing 2485 to 2944 fps muzzle velocity, and generated a (probably wildly overestimated) breech pressure of 90,000 psi(1) !! (Compare that to the pressures developed in the current cartridges on the chart above.)
In late 1918, work on the cartridge was transferred from Winchester to Frankford Arsenal, where it remained (almost exclusively) until well into WW2.(1) Design work on the weapon itself was performed by John Browning and Colt.(6)
During the ensuing years of development, the cartridge case design went through a series of metamorphoses. Case lengths from 4.08 inches to 3.80 inches were tried. Rimmed, semi-rimmed, and rimless case designs were considered. Both the 13mm German anti-tank round and a scaled-up 30-06 cartridge design were copied, with the latter finally winning approval. Projectile weights from 800 to 508 grains were tested. And cartridge overall lengths from 5.51 to 5.00 inches were explored.(1) (Compare with the stats listed in the chart above.)
Eventually, advances in tank armor outpaced that of anti-tank rifles, so the .50 BMG became, exclusively, a heavy machine gun caliber cartridge. The first machine gun was standardized as the M1921 and,(6) in 1924, the Caliber .50 Browning Machine Gun Cartridge was adopted in the form pretty much as we know it still today.(1)
Development Takes Off :
The onset of WW2 initiated a surge in development of the caliber and many design concepts were investigated just prior to, during, and well after the war. Loadings tried, at one time or another over the decades, include Ball, Blank, Grenade Blank, Dummy, Proof, Tracer (numerous variations !), Incendiary, Explosive, Shot, Frangible, Match, Hollow-Point, Tear Gas, Spotter (Observation), Armor Plate Test, Armor Piercing, Limited-Range Training, Short-Range Training, Limited-Range Training-Tracer, Short-Range Training-Tracer, Armor Piercing-Incendiary, Armor Piercing-Tracer, Armor Piercing-Tear Gas, Armor Piercing-Explosive, Armor Piercing-Incendiary-Tracer, Explosive-Incendiary, Explosive-Tear Gas, Incendiary-Tracer, Hi Explosive-Incendiary-Armor Piercing ("Multi-Purpose"), Hi Explosive-Incendiary-Armor Piercing-Tracer ("Multi-Purpose-Tracer"), (Plastic) Practice, (Plastic) Practice-Tracer, Flechette, Armor Piercing-Discarding Sabot, Armor Piercing-Discarding Sabot-Tracer, Caseless, Telescoped, "Folded," Lockless, Gyrojet, "Taper-Bore," "Triplex," Bio-Chem Warfare, etc.
It was during the 1930's that the problems of cracked case necks were cured by heat annealing. During the WW2 years, case mouth and primer sealants were introduced, to increase cartridge shelf life. In 1949 non-corrosive primer compounds were initiated. (Although the last plant didn't convert to non-corrosive until 1954.)(5) And in 1950, the troubles of tracer deterioration were reduced by the use of a projectile base sealing cap of metal foil or plastic.(7)
Since .50 BMG cartridge inception, projectile materials tested and either seriously considered or adopted have included: plastic, steel, copper, aluminum, brass, bronze, depleted uranium and various alloys too numerous to mention. The same could be said for cartridge case materials. These have included: steel, brass, aluminum, plastic, and various alloys too numerous to mention.
Through the decades, there have been metal cases with metal bullets, plastic cases with plastic bullets, plastic cases with metal bullets, metal cases with plastic bullets, and even metal cases with plastic AND metal bullets !!
Research and development on the .50 BMG caliber cartridge continues even today. Some of the latest (just within the last 10 years and just for USGI use) include : The M903 SLAP and M962 SLAP-T (see VHP Issue 1995 #4 for details), the Mk 211 MP (refer to VHP Issues 1993 #4 and 1994 #4), the newly redesigned M17 Tracer (see VHP 1997 #4 for details of this and the new tip color codes), the M858 Practice and M862 Practice Tracer (consult an upcoming issue of VHP), and some new designs whose details still remain confidential. (Watch for a future VHP article when the security wraps are removed.)
|.50 BMG Cartridge Case Headstamps (US Manufacturer Codes) (4)
||Frankford Arsenal, Philadelphia PA
||Des Moines Ordnance Plant, Des Moines IA
||Kelly Springfield, Allegheny Ordnance Plant, Cumberland MD
||Lake City Army Ammunition Plant, Independence MO *
||Milwaukee Ordnance Plant, Milwaukee WI
||Remington Arms, Bridgeport CT **
||Remington-Union Metallic Cartridge, Bridgeport CT
||Sparklet Devices, Dover OH
||St. Louis Ordnance Plant, St. Louis MO
||Stant Manufacturing Co., Connersville IN
||Twin Cities Ordnance Plant, Minneapolis MN
||Utah Ordnance Plant, Salt Lake City UT (late identifier)
||Utah Ordnance Plant, Salt Lake City UT (early identifier)
||Winchester (during initial prototype case development)
||Winchester (OLIN), E.Alton IL (modern identifier) *
||Winchester Repeating Arms, New Haven CT
* In this caliber, the only plants remaining in production.
** This code is also used by Raufoss of Norway
Countries known to have manufactured this cartridge include: Argentina, Australia, Austria, Belgium, Brazil, Canada, mainland China, Dominican Republic, Egypt, Finland, France, Germany, Greece, India, Iran, Iraq, Israel, Italy, Japan, Korea, Mexico, Netherlands, New Zealand, Norway, Saudi Arabia, Singapore, South Africa, Spain, Sweden, Switzerland, Syria, Turkey, UAE, UK, USA, and Yugoslavia.
Not to be forgotten, the .50 caliber machine gun itself has gone through many changes. Starting off as the M1921, there have been the M2, M3, M2HB, MG52, M85(6), and GAU-19 models. There have been aircraft versions, standard and heavy-barreled ground versions, air-cooled, water-cooled, and "quick-change" barreled versions, even a multi-barreled "gatling gun" variation. They have been mounted on aircraft, jets, helicopters, jeeps, trucks, "Hum-vees," half-tracks, APC's, tanks, "dune-buggies" (Fast Attack Vehicles), and ships.
The Future of the "Fifty Cal" :
Where does the .50 BMG cartridge fit in the scheme of things? What's so special about this caliber that it warrants such attention ? After all, this caliber is fast approaching its 80th birthday and, with current planning, it may well survive past its 100th birthday !! In active, front-line US military service, it's the oldest continuously serving caliber left in existence, next to the .45 ACP. While the .45 ACP cartridge was originally developed nearly 15 years earlier than the .50 BMG, it's been mostly replaced in service by the 9mm Parabellum. And the 9mm Parabellum cartridge wasn't even standardized by the US military until 1942.(4) The 30-06 caliber weapons preceded the .50 BMG cartridge by over 10 years, but that cartridge was finally retired from active front-line service by the end of the 1970's. The 7.62 NATO caliber wasn't even developed until the late 1940's and the 5.56 caliber wasn't in service until the 1960's. And yet, the US military's standard issue heavy machine gun caliber is still the .50 BMG. It, unlike the other calibers, has never been replaced; just upgraded.
To help answer some of these questions, start by seeing the table above to compare the .50 BMG with the 7.62 NATO (.308 Win) caliber, its next, closest, US military competitor. The 7.62 NATO, like the .50 BMG, has civilian, military, police, machine gun, match, and sniper applications.
For military users, the .50 BMG caliber cartridge offers a significantly larger payload volume over the .30 calibers. Also, with the speed and weight of the .50 projectile, muzzle energy is outstanding for a small arms caliber. This translates into a longer range bullet that can still deliver a punch. For both the military and civilian users, the .50 BMG projectile has superior wind-bucking capabilities, resisting wind drift. For more specifics, regarding the inherent advantages of the .50 BMG cartridge, refer to Very High Power Magazine (the official journal of the Fifty Caliber Shooters' Association) and other sections of the FCSA Web Page (www.fcsa.org).
For all its advantages, the .50 BMG cartridge would most likely have remained a machine-gun cartridge in the military's eyes, had it not been for the founders of the FCSA. In the 1980's, some people such as Skip Talbot, Marty Liggins, etc. saw the fifty's potential as a RIFLE cartridge for long-range, 1000-yard, CIVILIAN match/competition uses. The resulting private interest in this caliber spawned the FCSA. The success these civilian fifty shooters experienced in pinpoint, precision, long-range shooting, has led to the adoption of this caliber for sniper, counter-sniper, EOD, and anti-material applications by the US military; other government agencies; and many, larger, police SWAT/Emergency Response Teams.
With the development work continuing today, both at the individual shooter level, as well as that going on in government and industry, potential for the .50 BMG cartridge is still being to be explored. Advances in projectile design and materials, barrel rifling and treatments, etc. serve to illustrate that the .50 BMG cartridge is here to stay.
In Closing :
Numbers in parentheses above refer to sources listed in the bibliography section at the end of this article. They indicate the information preceding was provided by the reference listed.
For specific questions, current FCSA members (only) should refer to the inside cover of each issue of VHP Magazine for a list of "FCSA Consultants." FCSA Consultants are a benefit to paid members. These are people who volunteer their time to answer questions. They are available during the times listed and the only cost to the member for this service is the price of the long-distance telephone call.
The information listed here is for historical reference only and is not intended as reloading data. Always refer to the appropriate manuals for reloading data. Some loadings listed here are at, or near, maximum. Don't assume they are automatically safe for your weapon. Read and follow all prudent reloading practices, including "working up" your loads.
Before firing tracer or incendiary ammunition of any type or caliber, close attention should be paid to firing range conditions. Tracer and incendiary cartridges will easily ignite dry grass, leaves, or shrubbery.
Never fire discarding saboted ammunition in any weapon fitted with a muzzle device, unless you KNOW it's been certified for that weapon. Sabots are intended to discard immediately upon exiting the muzzle, about where your choke, flash-hider, muzzle brake, etc. is located. This could cause the device to be physically ripped away from the weapon, become damaged or blocked (adversely affecting subsequent projectiles), or material may be thrown back towards the shooter or spectators.
Never tumble live ammunition to make the cases brighter. Never fire any ammunition you suspect as having been tumbled to be cleaned. Tumbling can potentially pulverize the powder granules. As powder granule size is a means of controlling the burning rate, pulverizing them can significantly increase chamber pressures.
This article is only a brief overview and isn't intended to encompass all aspects of the .50 BMG cartridge. Consult with a knowledgeable source before firing any ammunition not personally known to the user. Buyer Beware ! Know Before You Load !
In the United States, some local jurisdictions (City, County, State, etc.) restrict or prohibit the possession, purchase, sale, or use of .50 BMG caliber rifles and ammunition. California residents, for example, are prohibited from possessing any caliber ammunition that is Armor Piercing, Incendiary, Tracer, Explosive, or any combination of the above. As VHP and this web site are international in scope, it is incumbent upon the reader to ensure that they are in full compliance with the laws affecting them.
The author, VHP magazine, and the FCSA accept no responsibility or liability for readers' attempts at applying the information in this article.
(1) - History of Modern US Military Small Arms Ammunition, Vol.1; F.W. Hackley, W.H. Woodin, & E.L. Scranton; ©1967; The Macmillan Co.; New York, New York.
(2) - Cartridges of the World - 5th Edition, Frank Barnes, ©1985, DBI Books, Northbrook, IL.
(3) - TM43-0001-27, Army Ammunition Data Sheets - Small Caliber Ammunition, HQ Department of the Army, 6/81, Including changes, Washington, DC, Unclassified.
(4) - History of Modern US Military Small Arms Ammunition, Vol.2; F.W. Hackley, W.H. Woodin, & E.L. Scranton; ©1978; The Gun Room Press.
(5) - TM9-1305-200, Small Arms Ammunition, HQ Departments of the Army & Air Force, 6/61, Washington, DC, Unclassified.
(6) - Machine Guns-A Pictorial, Tactical, & Practical History, Jim Thompson, ©1989, Paladin Press, Boulder, CO.
(7) - TM9-1901-1, Ammunition for Aircraft Guns, Departments of the Army & Air Force, 12/57, Washington, DC, Unclassified.
CW2 John Ferry, USA (ret.)
Boeing Defense & Space Group
Lomont Precision Bullets
River Valley Ordnance Works