Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Graphite – coal – or elemental carbon
Reexamination Certificate
2001-08-22
2003-06-10
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Graphite, coal, or elemental carbon
C508S115000, C508S116000, C508S155000, C508S148000, C508S165000, C508S167000, C508S169000, C508S219000, C086S019000, C102S448000, C102S511000, C042S076020
Reexamination Certificate
active
06576598
ABSTRACT:
TECHNICAL FIELD
This invention relates to protective and lubricating coatings for metals. More particularly the invention concerns compositions and methods for applying dry protective and conditioning surface coatings to firearms, firearm components, and to firearm ammunition and ammunition elements.
BACKGROUND OF THE INVENTION
It has long been recognized in the ballistics field that slightly oversized projectiles engage the undersized bores of firearms through which they pass on firing and cause fouling. Firing frequently heats the bullet to the softening point and perhaps the melting point and also heats the firearm barrel through which the projectile is fired. Microscopic surface defects or irregularities in the barrel increase frictional forces and remove minute metal particles from the projectile. These particles become imbedded into the surface of the inner bore of the firearm barrel.
Projectiles are generally manufactured from materials which are softer, more malleable, and which have lower melting points than barrel alloy. Upon being fired, the projectile generally conforms to the dimensions of the interior surface of the barrel. Typically firearm projectiles are made of cast/swaged lead bullets or jacketed bullets with a copper outer jacket and a soft lead core swaged into the copper jacket. In the case of shotguns, the firearm projectiles are made of pellet shot which is usually carried in a plastic “wad” or capsule.
The heat of powder and primer ignition and the heat of friction during the internal ballistic experience are high for a few milliseconds. Barrels can become very hot with extended periods of use, and projectiles can become so hot that they begin to soften, flow or melt on their trip down the barrel.
Microscopic surface asperities of the bullet and barrel surfaces mutually abrade each other. This abrasive action, along with heat and pressure, permits minute particles of projectile surfaces to be transferred from the projectile surface to the bore surface. In early stages, this problem of minute bullet particle build-up on the bore surface is called “copper wash” or “lead wash”. As the metallic build-up becomes more severe, such buildup is known as copper, lead, metal or plastic “fouling”.
It is well known that metallic fouling and foreign material in firearm barrels adversely affects firing accuracy. Metallic fouling irregularly alters the internal dimensions of the bore. When a bullet passes over a bore irregularity, the path of the bullet is altered by heat and pressure which is created as the bullet is forced to conform to the bore irregularity. This can cause the bullet to become irregularly shaped, out of symmetry, and consequently out of balance. Such asymmetrical condition causes the fired bullet to yaw and wobble inconsistently during flight compared to other fired bullets from one shot to the next. Thus, firing accuracy is diminished. Foreign debris of powder and primer residue, and carbon are abrasive and, along with any dirt or grit in the barrel, create irregular wear patterns on the relatively soft barrel alloy, similarly contributing to decreased accuracy.
The above described problems have been addressed with varying degrees of success using various lubricants including waxes, greases, soaps and dry lubricants applied to bullets and/or firearm bore surfaces. Oils and greases do not adhere well to bullets or bore surfaces and may pick up abrasive dirt, dust, or grit, or can break down into acidic and/or corrosive agents. Under the extreme temperatures and pressures associated with firing bullets, oils typically are burned off and cannot add much lubrication or protection against corrosion. Thus, the waste products of oils can end up contributing to the fouling problem.
Moreover, a safety hazard may be created with greases or oils when these fluid lubricants are “snow plowed” ahead of a fired projectile traveling down a firearm barrel. Tremendous hydraulic pressure can result when excess such oil or grease is present on the projectile, and can cause pressure excursions that bulge or burst barrels and/or blow up the locking mechanism.
U.S. Pat. No. 4,858,534 to Wallace discloses use of a lubricating composition comprising a polyolefin-base oil, amorphous silicon dioxide, and disodium octaborate tetrahydrate disposed in an indented ring around a bullet for lubricating firearm barrels through which such bullets are fired.
To avoid the pitfalls associated with oil- and grease-type lubricants, various solid lubricants have been suggested in the art, especially with small caliber bullets. Small caliber bullets have traditionally employed a full metal jacket or hollow point wherein no lead is exposed on the nose of the bullet. Typically, these bullets are fired through expensive premium grade barrels on match rifles, the bores of which have been lapped and polished.
While some success has been seen with the coating of smaller caliber target bullets with the dry powdered materials, less success has been achieved with larger caliber bullets. The primary problem associated with larger caliber bullets arises because the maximum build-up of the powdered coating material is insufficient to provide acceptable lubrication. Consequently, there is not enough coating material actually adhering to the bearing surface of the bullet to survive the transit down the length of the barrel. This is especially true in the rougher barrels of mass produced rifles, e.g. hunting rifles, where the larger bullets are fired at greater velocities from cartridges which have higher powder capacities. Therefore, unless a regular and standard regimen of cleaning the firearm barrel is followed, typically with abrasive mechanical brushing and strong chemical solvents and/or polishing and cleaning compounds, metallic fouling persists.
Various methods have been suggested for applying a layer of dry powdered molybdenum disulfide to the surface of bullets to provide an adherent layer.
U.S. Pat. No. 4,454,175 to Martin teaches a method of impact plating the surfaces of lead bullets with powdered molybdenum disulfide. Such impact plating comprises tumbling the bullets in a ball mill containing powdered molybdenum disulfide and steel shot. Such process is applicable only to bullets and cannot be utilized for coating bullets in a fully loaded cartridge or for conditioning the inner bore of a firearm barrel.
For the latter purpose, Martin et al., in U.S. Pat. No. 5,378,499 teach lapping the bore of a firearm barrel by repeatedly firing through it bullets which have previously been coated with an abrasive such as diamond powder, boron nitride, boron carbide, silicon carbide, and the like.
To overcome the drawbacks associated with coating bullets with dry, powdered materials, various methods have been suggested which employ liquid compositions.
U.S. Pat. No. 4,196,670 to Vatsvog, for example, teaches a process for uniformly coating bullets with molybdenum disulfide lubricant by spray or dip coating the bullets with a suspension of molybdenum disulfide in an epoxy phenolic resin. Vatsvog further teaches that the wet-coated bullets are then allowed to air dry. For an effective and rapid cure of epoxy phenolic resins, however, the resin coating should be heat cured, which rules out coating of cartridges already assembled with propellant and igniter. If, on the other hand, the coating is allowed to air dry, long curing times are required before the coating is ready for its intended use, whereby such process is uneconomical.
U.S. Pat. No. 5,062,974 to Van Meter discloses a surface treatment for firearms and bullets comprising finely divided molybdenum disulfide, an alkali metal molybdate and a volatile organic solvent such as trichloroethane. Van Meter teaches that the sodium molybdate adheres to the underlying metal substrate, with the molybdenum disulfide adhering to the sodium molybdate.
U.S. Pat. No. 6,090,756, of common inventor ship herewith, teaches application of liquid suspensions of molybdenum disulfide compositions for ballistic conditioning purposes.
It is one object of the present inve
McAvoy Ellen M.
Wilhelm Thomas D.
Wilhelm Law Service
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