Advantages and benefits of Ni B, nickel boron, and nitro met, salt bath nitride on AR bolt carrier group, barrel, and gas tube assemblies. This is an inexpensive modern technology process to protect the surface of alloy steel against wear as well as corrosion. The traditional manganese phosphate process on mil spec bolt carrier groups and chrome Molly barrels, has been outdated for about a decade as related to protection from wear and corrosion on chrome Moly alloy steel parts, components in the aerospace industry, small arms & munitions, and performance motorsports industries.
The protection gained, and most importantly retained, by modern plating methods such as nickel boron is far superior to older outdated processes i.e. manganese phosphate and hard chrome. Manganese phosphate degrades in a short time and is removed from alloy steel surface by reciprocation of the bolt carrier group. Then the surface is prone to rust and corrosion, as well as wear relative to abrasive content such as sand and grit. Coefficient of friction is affected at this point, and the gun can run sluggish or experience reliability issues especially if not properly lubricated. Most importantly is the gas ring area where the bolt and gas rings mate and seal the pressurized area of the inside diameter of the bolt carrier group. Nickel boron coated carriers have the reduced chance of premature gas ring wear which can cause blow by, or gas leakage, causing the weapon to malfunction.
While barrel life expectancy is always relative to rate of fire in semi auto or full auto mode, we have seen barrel life in the 40,000 to 80,000 round count range with nominal 1/4 minute of angle loss in accuracy at that level with unprocessed barrels. Our initial 416 stainless steel test barrels were not processed with Nitro Met – nitride process, and still exhibited phenomenal barrel life and accuracy relative to elevated sustained rate of fire. Stainless steel barrel material is far superior to chrome Moly steel at a very reasonable and affordable price. Its life expectancy is improved with the use of a nitro met salt bath Nitride process, which is why the modern firearms industry has migrated towards those types of plating processes versus traditional hard chrome, which was available to Eugene Stoner in 1957 when he designed the M-16 AR 15 platform. Modern materials and technology have long surpassed the viability of hard chrome and manganese phosphate in small arms production.