Ball propellant


Ball propellant is a form of nitrocellulose used in small arms cartridges. It has been trademarked as Ball Powder by Olin Corporation and marketed as spherical powder by Hodgdon Powder Company. Ball propellant can be manufactured more rapidly with greater safety and less expense than extruded propellants. Ball propellant was first used to load military small arms cartridges during World War II and has been manufactured for sale to handloading civilians since 1960.

History

The United States military replaced gunpowder during the first decade of the 20th century with smokeless powders formulated from nitrocellulose colloided with ether and alcohol. Large quantities were manufactured for World War I and significant amounts remained unused after the war. Nitrocellulose deteriorates in storage, but military quantities of old smokeless propellant were sometimes reworked into new lots of propellants.
Through the 1920s Dr. Fred Olsen worked at Picatinny Arsenal experimenting with ways to salvage tons of cannon powder manufactured for World War I. Dr. Olsen was employed by Western Cartridge Company in 1929 and developed a process for manufacturing ball propellant by 1933. Reworked powder was dissolved in ethyl acetate containing small quantities of desired stabilizers and other additives. The resultant syrup, combined with water and surfactants, is heated and agitated in a pressurized container until the syrup forms an emulsion of small spherical globules of the desired size. Ethyl acetate distills off as pressure is slowly reduced to leave small spheres of nitrocellulose and additives. The spheres can be subsequently modified by adding nitroglycerin to increase energy, flattening between rollers to a uniform minimum dimension, coating with deterrents to retard ignition, and/or glazing with graphite to improve flow characteristics during blending.
This manufacturing process also worked with newly manufactured nitrocellulose. Manufacturing time was reduced from approximately two weeks for extruded propellants to 40 hours for ball propellants. Rate of burning is controlled by deterrent coatings eliminating precision forming and cutting machines required for surface area control of extruded propellants. Safety was improved by performing most of the manufacturing process in water. Olin subsidiaries began manufacturing ball powder specification WC846 for.303 British ammunition during World War II. Hodgdon Powder Company salvaged 80 tons of WC846 propellant from disassembled.303 British military rifle cartridges in 1949 and sold the propellant to handloading civilians as BL type C. The C was to indicate the propellant burned "cooler" than traditional Improved Military Rifle propellants. Olin continued manufacturing WC846 for both civilian ammunition and 7.62×51mm NATO cartridges after the war. Manufacturing operations moved in 1969 from East Alton, Illinois, to the St. Marks Powder plant in Crawfordville, Florida.

Constituents

Olin's safety data sheet indicates the following composition of ball propellant:
Aside from the manufacturing advantages, ball propellants metered more uniformly through measuring machinery used to load cartridges, had a longer storage life in loaded cartridges, and reduced erosion of rifle barrels when those cartridges were fired. On the other hand, ball propellant loadings were more difficult to ignite, produced brighter muzzle flash, and left heavier fouling in rifle barrels than had been common with extruded propellants. Some ball propellants burned satisfactorily over a narrower pressure range than extruded propellants. Some handloaders accustomed to extruded propellants had difficulty determining appropriate charges for the unique components they were assembling. Light loads might fail to ignite and burn properly while heavier loads might cause abrupt pressure increases to dangerous levels.
Fouling difficulties increased as military loadings shifted from the.303 British and 7.62 NATO to the 5.56×45mm NATO. Some propellant lots clogged the gas tube of M16 rifles until concentrations of calcium carbonate stabilizers were reduced in 1970 as reformulated WC844 for the 5.56mm NATO cartridge. Civilian handloaders experienced similar fouling problems with smaller bore diameters. Some attributed the problem to residues of unburned deterrent coatings and suggested using magnum primers to improve ignition and burning at lower pressures. Ignition was ultimately improved by blending in a small percentage of uncoated propellant granules to improve the performance of standard primers.

Expanded handloading options

Hodgdon's original 80 tons of surplus BL-C introduced ball propellants to handloaders. Handloaders were ready to pay for newly manufactured ball propellants when the surplus supply was exhausted about 1960.

Hodgdon