M14 Rifle Lubrication Information

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M14 Rifle Lubrication Information

Post by Zeliard »

Originally posted by Gutkowski.

Soft Lubricants – Oils, greases and sprays are used to lubricate moving parts within a firearm to facilitate proper function and minimize parts wear. Soft lubricants also provide modest protection against corrosion where applied. Aside from military specification grease, there are a number of commercially formulated greases that provide adequate lubrication for the M14 type rifle in all but the most severe service conditions. Most firearms lubricants today are petroleum based oils and greases. Soft lubricants often have additives for improving lubricity, corrosion resistance and viscosity. Soft lubricants do not perform well in cold weather and do break down after a period of time.

FM 23-8 specifies rifle grease should be applied at a number of contact points on the M14 as a part of normal maintenance: bolt locking recesses, the bolt camming lug on the hammer, operating rod camming surfaces, and the lip of the receiver that contacts the rear top edge of the bolt. As part of normal maintenance, M14 gunsmiths may also recommend a light film of rifle grease in 1) the operating rod channel 2) the operating rod saddle that contacts the barrel 3) the bolt roller 4) the receiver bolt raceway 5) between the top of the lip of the front band and the bottom of the stock ferrule 6) the inside of the cylindrical portion of the operating rod 7) the inside diameter of the operating rod guide 8) the operating rod spring guide 9) the bottom of the rear sight base and 10) sides of the rear sight aperture. Grease should be removed and reapplied yearly to prevent solidification. U. S. Army armorers applied MIL-G-10924D specification grease to M14 NM rifles. The official name of this grease is “Grease, automotive and artillery” and is commonly referred to as “GAA.”
Hard Lubricants – It may seem detrimental for very hard surfaces to be in bare sliding contact with each other but friction and wear can be significantly reduced with some hard surface finishes. In other words, a solid material can be a lubricant. In the M14 rifle, this is not only possible but has already been achieved. The benefit of applying a hard, smooth finish to the M14 barrel bore was realized in 1956 (see M15). The all chromium plated firing pin has proven itself enduring and lubricious since the mid-1960s (see Miscellaneous Notes on USGI Parts). The XM25, M25 and M14SE rifles employ gas pistons with very hard finishes in combat conditions. Some commercial M14 type receivers and parts have been nitrocarburized since 1985. As part of a custom rifle project, Century Arms International Norinco M14 Sporter receiver serial number C08610 has been dense chromium plated. Proper selection and application of hard, smooth finishes does enhance the service life of M14 rifle parts.

Ceramic coatings have been applied to metal cutting tools for decades. Titanium carbide coated cutting tools were introduced to industry in 1969 and titanium nitride coated gear cutters were first used in 1980. Ceramic coatings are used on metal cutting tools because they are abrasion resistant, very hard, and chemically inert and have a low coefficient of friction. The benefits are longer tool life, higher cutting speed, higher feed rate and less machine tool down time. One such ceramic coating is titanium nitride. Titanium nitride is applied to clean metal parts by the physical vapor deposition method. Briefly, this process entails evaporating a very thin layer of titanium on to the part inside a nitrogen gas chamber. The titanium nitride layer is typically 0.0001 ” to 0.0002 ” thick. This process is done at a temperature low enough (400 to 900 degrees Fahrenheit) so that the metallurgy of the part being coated is not affected. Depending on the ingredient composition, the color of titanium nitride coatings can be any of several hues of brown or gold. The surface hardness can be made as high as 85 HRC.

Titanium nitride coated gas pistons became part of the build specification for XM25 rifles by 1988 (see XM25 and M25). The M14 SE Semi-automatic Sniper System is built with a dense chromium plated gas piston. The USGI M14 gas piston material specification is heat treated AISI 416 stainless steel. Typical USGI gas piston surface hardness ranges between 74.5 and 77 HRA (approximately 42 HRC). A gas piston coated with titanium nitride results in a surface hardness ranging from 70 to 80 HRC. Thin dense chromium plated gas pistons have surface hardness of 80 HRC. The advantages of a hard and smooth finish gas piston are as follows:

1) Anti-galling and anti-seizing properties – Galling is the welding of two metals together as they slide against each other. Galling and seizing are not desirable in the M14 rifle gas system. Titanium nitride and dense chromium coatings are harder but have lower coefficients of friction than stainless steel. These characteristics result in a slicker surface than the bare stainless steel gas piston. In effect, the hard finish is a solid lubricant in this application. Consequently, there is less gunpowder and primer residue buildup. Gunpowder and primer residue buildup does cause a very minute amount of seizing between the gas cylinder and gas piston.

2) Corrosion protection – Titanium nitride and thin dense chromium finishes have better pitting corrosion resistance than martensitic stainless steel.

3) Thermal protection – Thin layers of titanium nitride and dense chromium give the substrate metal, AISI 416 stainless steel in this case, better resistance to the effects of heat. The higher resistance to heat extends the service life of the gas piston much like titanium nitride coated metal cutting tools last longer than those that are not coated.

4) Better compression – The hard finish extends the life of the piston grooves. A sharper groove edge will provide compression for a longer amount of time plus it removes more of the gunpowder and primer residue from the cylinder wall than a bare gas piston.

5) Easier cleaning – Cleaning the piston is made easier since the gunpowder and primer residue does not adhere as well as on bare gas pistons.
Nitrocarburizing is a thermochemical process that improves the surface properties of iron or steel parts. It increases surface hardness to 60 HRC, reduces the coefficient of friction, improves wear resistance and enhances corrosion resistance of the metal treated. M14 type receivers, gas cylinders, gas cylinder locks, gas cylinder plugs, front bands, hammers, triggers and scope mounts have received the benefits of nitrocarburizing treatment.
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