Molybdenum was discovered by Carl Wilhelm Scheele of Sweden in 1778. This element has an atomic weight of 95.94 and an atomic number of 42. It is silvery-white in color and represents one of the hardest refractory metals; i.e., resistant metals with a melting point of 2,617? C. It serves as a component of steels, cast irons, and non-ferrous metals to produce strong alloys with high resistance to corrosion.
Additional uses for molybdenum include aircraft and missile parts, wire filaments as well as protective coatings for other metals, particularly titanium. Some molybdenum chemicals are used as dyes. Molybdenum trioxide increases adhesion of enamels for coating and molybdenum disulfide is used as a lubricant in greases in oils.
The morphology of molybdenum disulfide or “moly” is a hexagon crystal composed of a lattice of layers of sulfur and molybdenum atoms that retain their laminar structure even in a finely pulverized state. Moly has a very low coefficient of friction even in higher heat ranges to 750? F, and it possesses an extraordinary affinity to stick to metal, particularly if rubbed into the metal.
Moly is also used to coat bullets, a process that has been claimed to reduce barrel fouling; to increase bullet accuracy; to reduce chamber pressure, thereby permitting increased powder charges that result in a net gain in muzzle velocity; and to extend barrel life — all attributes near and dear to the readers of this magazine. There is some evidence that moly also increases a bullet’s ballistic coefficient which results in higher velocities with flatter trajectories. This is apparently due to an earlier-than-normal stabilization of coated bullets versus uncoated bullets. In this regard, the greatest benefits of moly coating appears to be found in heavier bullets with their long bearing surfaces.
The pros and cons of moly have been reviewed extensively by a number of articles appearing in Precision Shooting and Shooter’s News magazines during the past several years. In addition, discussions, some extremely heated, are being conducted on the Internet, particularly with the Centerfire Benchrest Shooting ([email protected]) and Precision Rifle ([email protected]) mailing lists. My impression is that pros are currently outweighing the cons, with the debate now centering on finding acceptable evaluation criteria and contrasting moly’s benefits against those found with non-moly products.
A moly kit is manufactured by Nostalgia Enterprises Co. (NECO) who has a patent on the coating process (NECO-Coat™) and has licensed it to a number of vendors. To my knowledge, the only commercial cartridge manufacturers using moly are Norma and Black Hills, both licensed by NECO. Winchester does market cartridges with bullets coated with Lubalox. Lubalox turns out not to be a moly, but a black oxide (see sidebar article). Berger Bullets Ltd. is selling bullets coated with moly and other manufacturers may be using moly as well.
John Gammuto, Executive Editor, announced in the March, 1997 issue of Shooter’s News that he will publish objective reviews of bullet coating applications as long as they are documented. More than likely during the next five years, both pros and cons regarding moly and non-moly products, which are certain to emerge, will be challenged on these pages until some sort of consensus is reached within the shooting community or until a new controversy appears that replaces the current one.
Rather than adding to the controversy, this might be a good time to examine existing, emerging and untried methods of application of molybdenum and any other bullet coating that might soon arrive in the ads of your favorite shooting magazine. This article reviews four methods of molybdenum application: 1) peening, 2) aerosol, 3) covalent impregnation, and 4) vacuum evaporation. The first two approaches utilize molybdenum disulfide (moly), while the covalent impregnation utilizes molybdenum phosphate and vacuum evaporation utilizes pure molybdenum. In addition to differences in the ease of application, differences exist in the appearance of the molybdenum after its application to the surface of the bullet as revealed by scanning electron microscopy. Whether the latter is relevant to ballistic characteristics is unknown at this time.
Of the four methods, the peening of moly is the oldest and its ballistics benefits have been reviewed extensively. The aerosol method became commercially available recently and its ballistic benefits, if any, have not been reviewed at the time of this writing. A new product that utilizes a covalent impregnation method of molybdenum phosphate was originally designed for the coating barrel bores and the manufacturer had not considered using it to coat bullets until I brought the idea to their attention. As a result, Nosler has begun to test the product. The last method, vacuum evaporation, was my own idea and was included as a method for comparison to the other three methods. It has not been tested so ballistics benefits, if any, are unknown.
Thus, four methods to apply molybdenum to the surface of bullets are presented, with three out of the four not tested as evidenced by the lack of published reports. Results on the aerosol methods more than likely will start appearing in print during the next six months. With regard to the covalent impregnation method, the intent of the manufacturer was to market its product to coat barrel bores so results will be difficult to compare with the other three methods; however, if some of Nosler’s research appears to be promising, direct comparison can be made. Finally, the vacuum evaporation method will require expensive equipment, and thus, it may be prohibitive for the average reloader, but may be economically beneficial for manufacturers who are coating large numbers of bullets.
REVIEW OF METHODS:
Peening – The method of molybdenum coating that is most familiar to the shooter is where moly is applied to bullets in at least two tumbling or shaking operations using carnauba wax during the second step. Steel shot in one tumbler/shaker is used to used to peen the moly to the surface of the bullets; and new shot, usually in a second tumbler/shaker, is used to cover the moly with carnauba wax. Peening moly is not restricted to bullets. NASA developed a process called “Peen Plating” which requires two machines, one for cleaning the surface and one for coating. Once the coat is applied, it is bombarded with high speed peening hammers consisting of plastic hammers to steel shot.
Another product called Danzac™, offered by Kinkaid’s Customs (P.O. Box 36023, Canton, OH 44735), has been reviewed in several articles published in Shooter’s News. Kinkaid’s Custom claims their product is equal to or is better than moly plus it has the advantage of omitting the carnauba wax peening step. The composition of Danzac™ appears to be proprietary; but it may be another metallic salt, such as tungsten disulfide.
Aerosol – During the past several months, several manufacturers have come forth with a moly aerosol product. KG Bullet Coat (KG Products, 537 Louis Drive, Newbury Park, CA 91320) is marketing an moly aerosol spray kit which consists of a can of moly suspended in an unidentified solution plus a spray gun kit named Preval®; the latter manufactured by Precision Valve Corporation of Yonkers, NY and can be purchased in most hardware stores. The moly suspension is placed into a glass bottle which is part of the Preval® kit, and then it is propelled by a mixture of AERON A-70/DME, propane, isobutane and dimethylether. In addition, Markman, Inc. of Burlington, WI is marketing an aerosol application kit called Ms. Moly™. The solvents with propellants are part of the kit. Other than the presence of moly, additional ingredients in these two products are unknown, but at least three essential components are required to coat bullets properly: moly, a solvent and a binder. The solvent serves as a carrier to spray and the binder acts to trap the binder onto the applied surface.
Because of the UPS strike during the period of my tests, I was unable to obtain the two commercially available aerosol moly products. Thus, I asked Tom Johnson of Translube (PO Box 6000-152B, Pahrump, NV 89041) to prepare a moly mixture and send it Federal Express. Tom has had years of experience in the manufacturing of lubricants. His specialty is lubricants designed for titanium parts used in the aerospace industry.
The aerosol method is an easier to apply moly to bullets than the peening method. Recommended method is to line up bullets, spray and allow them to cure with or without a thermal curing. In addition, the method allows coating of bullets previously seated in the cartridge case; however, only the bullet’s bearing surface that is exposed outside of the cartridge case will be coated.
Covalent Impregnation – In the July issue of Varmint Hunter magazine, Dr. Ken Howell revealed a new product, initially called Moly Bond but now called Moly-Fusion™. It’s a liquid solution of molybdenum phosphate that is intended for electroless plating of metal surfaces. It is distributed by W. L. R. Perry (Professional Options, 1304 W. Main, Lewisville, TX. 75067 [972-539-1980]) as a treatment for bores of gun barrels. At the time of the Ken’s article, he had not tried the product, but it was clear that he saw its potential for the shooting community. Intrigued with electroless molybdenum phosphate plating, I contacted “L. R.” for more information. L. R. and the parent company, MDECHEM (Houston, TX) were most helpful in providing detailed information regarding a recent discovery, covered by U. S. Patent #5,310,419.
The patent describes a set of novel acid/base reactions involving stabilized inorganic amido complexes in which REDOX (reduction in the electrolyte/oxidation in the metal) reactions to take place on the surface of a metal. Moly-Fusion™ contains stabilized, negatively charged metal ions of molybdenum and phosphate which are able to electroplate molybdenum ions in a liquid solution at a neutral pH.
In order to verify whether a covalent bond was established between the negatively charged ions and the metal surfaces, Dr. Earl Graham and colleagues from the Department of Chemical Engineering at Cleveland State University conducted tests that demonstrated covalent bonds were established. They further reported a reduction of the coefficient of friction between metals (Lubricants World, May, 1996, p. 160).
Moly-Fusion™ originally was marketed as a molybdenum treatment for the bores of barrels. The manufacturer’s literature contains a statement that Moly-Fusion™ will not bind to pure copper nor titanium. It seemed reasonable that some binding would occur with bullet jackets since they are composed of a copper alloy. For example, Nosler’s recent preliminary tests with .308 caliber bullets that had been dunked in the Moly-Fusion™ revealed a reduction of 1,000 psi in chamber pressure and of 30 fps in muzzle velocity, both signs that Moly-Fusion™ is interacting with the bullet’s jacket.
Vacuum Evaporation – Film deposition by vacuum evaporation is represented in a number of industrial applications, most notably the “coating” of optical lenses and prisms to minimize surface reflections. As a result, large and small equipment packages are commercially available which are easily adaptable for metal deposition. These units contain a pumping system consisting of a mechanical forepump and high-capacity diffusion pump.
In order to coat an object with a metal, the metal is evaporated by heating it to a suitable temperature in the vacuum. In the absence of atmospheric gases, atomic metal is coated on the object’s surface one atom at a time. The metal may be granular, powder, wire, ribbon or foil. In most cases, visual estimation of thickness is determined by placing a piece of white porcelain next to the material to be coated.
I was unable to find a report of molybdenum or a molybdenum salt evaporation onto bullets. In this study, molybdenum wire rather than molybdenum disulfide rods were used. Molybdenum disulfide rods were not available except by special order.
Untreated Bullets – Untreated jacketed bullets and treated jacketed bullets from obtained one manufacturer were used for this study. They were soft-nose, boat-tails. Untreated bullets served as controls. Scanning electron microscopy (SEM) revealed that the surface of the bullet’s jacket contained indentations positioned parallel to the bullet’s long axis (Figure 1). Other indentations were found, but in random locations on the bullet’s jacket. The lead composing the soft-nose did not display longitudinal indentations similar to those found on the bullet’s jacket.
Conclusions: More than likely the indentations oriented parallel to the long axis were etched into the bullet’s jacket during the swaging process, while the indentations found in random locations were due to handling during packaging, transport etc.
Since this study examined jacketed bullets from only one manufacturer, it is impossible to state whether these indentations are characteristic of jacketed bullets from other manufacturers as well. However, it should be evident that electron microscopy reveals structures difficult to resolve even by light microscopy, not to mention the unaided eye. In any event, it is reasonable to assume that jacket indentations would be lost during contact with the rifling of the barrel and probably would have no measurable effect on the bullet’s ballistics.
Peening Without Moly – Questions have been raised regarding potential damage to the bullet jacket by
peening with steel shot in either a tumbler or shaker. Bullets undergoing peening without moly and carnauba wax were examined. Peened bullets, without the aid of magnification, revealed a dull, matte finish similar to a bead blasted finish. With SEM, the surface of the bullet jacket revealed parallel, evenly-spaced ridges aligned to the bullet’s long axis (Figure 2). These structures should not be confused with the swaging indentations seen in the controls because of differences in appearance and size. These indentations were not found. In addition, cavities were found in the lead soft points. Such cavities were not observed in control bullets.
Conclusions: Peening with steel shot alone alters the bullet jacket’s surface by creating parallel, evenly-spaced ridges and cavities in the lead soft-point. On the other hand, swaging indentations found on control bullets were not evident, probably lost during the peening process. Again, it seems reasonable to assume that the ridges created by the peening would be lost during contact with the rifling of the barrel. The cavities found in the lead soft points varied in size. Whether their presence affects the aerodynamics of the bullet is not known.
Peening With Moly Followed By Attempted Removal – The surface of bullet jackets that had been peened with moly and carnauba was examined next. To view the jacket’s surface, it was necessary to remove the moly and carnauba wax. Attempts were made by placing bullets into five different organic solvents, with and without sonification, for 1 hour. The moly remained attached to the bullet, however the carnauba wax dissolved. Evidence for the lack of removing moly was no noticeable change in the color of the clear solvent and the color of the bullet. Evidence for the removal of the carnauba wax was a loss of the bullet’s “shiny” appearance. Consideration was given to physically removing the moly by rubbing; however this was abandoned because rubbing would introduce artifacts on the surface of the jacket. Finally, it should be noted that bullets coated with moly alone — by immersing them in moly powder — could be cleaned with the solvents and sonification, but bullet jackets still showed signs of moly adhesion.
Conclusions: Once moly has been peened to the bullet jacket, it appears that it can not be removed by organic solvents and sonification. Without peening, most can be removed. Peening clearly increases the adhesion of the moly to the jacket, but a small amount of moly adhesion exists without peening.
Peening With Moly – Bullets peened with moly and carnauba wax were examined by SEM. The moly/carnauba wax mixture covered the entire surface of the bullet, including the lead soft point (Figure 3). The mixture displayed a rough surface with raised projections. In some regions of the bullet’s surface, parallel, evenly-spaced ridges were evident. Again, cavities were found in the lead of the soft-nose.
Conclusions: SEM of the moly-carnauba wax mixture revealed small surface projections and parallel, evenly-spaced ridges. Since the surface of the jacket was not visible because of the presence of the moly-carnauba wax mixture, it was not apparent whether its surface was similar in appearance to the surface of bullets peened without the moly and carnauba wax. However, because parallel, evenly-spaced ridges were found, it seems reasonable to assume that their presence is due to the peening process. Finally, it is reasonable to assume that peening with and without moly creates small cavities in the lead of the soft nose. Again, whether these cavities will affect the aerodynamics of the bullet is unknown.
Aerosol – Moly applied to bullets with an aerosol was easy, fast and without mess. The bullets were sprayed until they appeared dark in color. No attempt was made to measure the amount of moly being applied to the bullet’s surface. After spraying, bullets air-dried within minutes. Thermal drying was not attempted. Dried bullets displayed a dull black finish. The moly was resistant to coming off during handling.
SEM revealed that the entire surface contained a dense coat of moly (Figure 4). It was clear that the moly thickness was much greater than seen with the bullets peened with moly. The aerosol moly coat appeared rougher than the peened moly coat. In some regions of the bullet the moly layered as flat sheets; i.e., analogous to flagstones. No parallel, evenly-spaced ridges were observed.
Conclusions: Bullets were sprayed until they were dark. No attempts were made to use shorter spraying times. The major difference when contrasted against the moly-carnauba wax treatment is the ease of application with the moly-aerosol mixture. The entire process was completed within approximately 10 minutes. Whether the moly-aerosol coat reached a desired thickness to yield maximum results is not known. Is there a desired thickness that yields maximum results? How much is enough? Will too much adversely affect the ballistic characteristics? Clearly, this is a study for the manufacturers of moly-aerosol mixtures.
During the preparation of this manuscript, Ms. Moly™ arrived. I sprayed some bullets in order to contrast their appearance to the bullets sprayed by Tom Johnson’s aerosol-moly mixture. I noticed that the moly from Ms. Moly™ came off onto my hands during handling, a possible indication that a binding agent was not used in its formulation. The moly-carnauba wax mixture did not rub off the bullet as easily as the Ms. Moly™ mixture and this was also true with Tom Johnson’s moly-aerosol mixture containing a binder. Even though I didn’t believe so at the time, it is possible that I over-sprayed with Ms. Moly™. Another possibility is that the moly concentration might be too high. Clearly, studies are necessary to determine, “How much aerosol-moly is enough?”
SEM of the moly-aerosol revealed a coating that appeared rougher than the moly-carnauba wax applied by peening. Differences in appearance are probably due to the different method of application. In some areas on the bullet’s surface, moly from the aerosol mixture appeared to dry as sheets, one on top of another. Finally, even though the moly seen in the peening method appeared different from that seen in the aerosol method, it is reasonable to assume that the only practical difference might be the thickness of the moly.
Covalent Impregnation – Moly-Fusion™ is a liquid and the first application chosen was a pump spray. With this application, the Moly-Fusion™ “beaded-up” on the bullet’s jacket. Bullets, pretreated with organic solvents including ethanol to remove any oils, exhibited less beading. With the second application, bullets were dipped into the Moly-Fusion™; but upon removal, the liquid formed beads on the bullet’s jacket. The impregnation or etching process could be visualized under the beads within one minute and the bullets dried within several minutes. To the touch, the bullet felt slippery which can best be described as a “soapy slippery.” Bullets coated with moly by peening and aerosol treatments did not display a similar slippery feeling.
SEM of Moly-Fusion™ treated bullets revealed raised areas where the beads of Moly-Fusion™ dried (Figure 5). Diameters of the raised areas varied from what could be seen with the naked eye to areas that could only be resolved with higher magnifications. The raised areas revealed that the molybdenum phosphate etching appeared as convoluted strands of material on the surface of the bullet’s jacket.
Conclusions: A spray application resulted in Moly-Fusion™ beading on the surface of the bullet and led to an uneven covering of the surface. Pretreatment with organic solvents promoted less beading. An aerosol application was not tried, but this treatment would probably lead to the formation of smaller droplets rather than the larger droplets seen with the spray application. Dunking and then removing the bullet from the Moly-Fusion™ also created beads. It is reasonable to assume that the beading is due a lack of chemical interaction between Moly-Fusion™ and cooper. What interaction that did occur would be due to the alloys in the jacket.
For this study, placing the bullet into the Moly-Fusion™ until the etching was completed was not attempted because the surface of the jacket found under a bead Moly-Fusion™ could be compared to a nearby surface where bead formation did not occur. However, immersion of the bullet would ensure an even covering with the molybdenum phosphate, but the question would be “How long to treat?” In order to insure a uniform thickness of molybdenum phosphate, bullets would have to be immersed in the Moly-Fusion™ and checked for thickness at varying time intervals after removal. Clearly, this is a study for the manufacturer. The bullets were slippery to the touch which supports the manufacturer data that Moly-Fusion™ reduces drag coefficient.
The appearance of Moly-Fusion™, as convoluted strands of material, was a different morphology from the moly observed in the first two applications. It should be kept in mind that Moly-Fusion™ is molybdenum phosphate while the early two applications were molybdenum disulfide and differences in morphology should be expected. Whether this product will make a contribution to precision shooting will be determined on the rifle range. Finally, based upon my results, it seems reasonable to assume that the manufacturer’s initial use of Moly-Fusion™ to treat barrel bores might be a better use of the product.
Vacuum Evaporation – Molybdenum wire was vacuum evaporated until the bullet’s jacket turned dark. SEM of the bullet revealed a smooth surface with random indentations seen on control bullets were not visible, presumably due to the presence of the molybdenum (Figure 6). Of all of the methods tested, the surface of these bullets were the smoothest.
Conclusion – Molybdenum can be vacuum evaporated onto the surface of bullet jackets, a fact that was not unexpected. It appeared as a homogeneous coating. The question whether molybdenum disulfide (moly) can be vacuum evaporated is more than likely yes and probably will have a similar appearance as the pure molybdenum. The unavailability of moly in a solid form prevented an evaluation, so this is only speculation. Bullet coating by vacuum vaporization does have certain appeal, providing that large batches of bullets are being coated and that the thickness of the coat can be controlled.
I can’t close this article without taking a peek into the future as to any new coatings that might possess a better overall advantage or perhaps, possess a singular advantage over existing products. I’m not a great one for re-inventing the wheel, so I tend to search for information regarding what others have found. A literature survey can yield a wealth of information regarding available surface coatings, both proprietary and non-proprietary products.
For example with the latter, Argonne National Laboratory has studied the development of coatings for improved friction and wear reduction properties, including boric acid, near-resistant carbide, nitride and boride coatings, lubricious oxide, and diamond and diamond-like carbon films. Even though their studies were directed toward engine surfaces found in low-emission, high-fuel-efficiency transportation systems, some of these coatings may have other applications; i.e., bullet coating. Costs may be prohibitive in some cases, but in other cases, such as boric acid, costs would be minimal. The Argonne National Laboratory has an Industry Liaison: Industrial Technology Development Center Building 900, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439. A novel coating material may be waiting for some entrepreneur interested in marketing a “magic” bullet coating that will prolong barrel life and allow all of us to shoot tighter groups.
Now wanting to be left out of the excitement of discovery, I’m in the early stages of several projects. One project examines molybdenum sulfide rods vacuum-vaporized onto bullets with varying thicknesses. Another project examines a promising proprietary compound that is currently used in the space industry to reduce galling of titanium parts. If results prove to be promising, I’ll present my research data for your consideration in a future article(s).
My guess is that in the future I shall not be alone presenting research data on new bullet coatings. The race has just begun. Seems to me that there is room for more participants.
Note: Bullets used for this study were .308 Speer 165-gr. soft nose boat tails which are packaged loose in a box of 100. Molybdenum disulfide (2 mm size) and carnauba wax (refined no. 1) were purchased from Aldrich Chemical. Both were reagent grades. Peening with and without moly was performed by standard methods for a period of six hours. Moly mixture for aerosol treatment was provided by Tom Johnson. In addition to the moly, a solvent and binder were present. Their identities were not revealed to me. Application of the moly mixture was by Preval® spray gun kit mentioned in the article. Application of Ms. Moly™ followed manufacturer’s instructions. Vacuum evaporation of molybdenum wire was performed in a Denton vacuum evaporator. Scanning electron microscopy was performed on a Philip 505 scanning electron microscope.