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History The story of the M-16's procurement and the evolution of its components over time is fascinating to a gun-nut like me. The bolt carrier group (BCG) is an important part of that story.  As Eugene Stoner designed it, the BCG was originally chrome plated inside and out. This was an excellent finish for a component that would see harsh conditions especially considering the dirty nature of the rifle's newly patented "direct impingement" system.  Over time however, …

AR15 BCG finishes (l-r) Toolcraft Titanium Nitride, BCM BCG with Robar NP3+, Toolcraft Nickel Boron, Toolcraft Black Nitride, Colt BCG refinished in Chrome with Nickel Boron Gas Key, Toolcraft Diamond Like Carbon (DLC) Finish, Toolcraft Chrome Phosphate (Parkerized) There are a wide variety of finishes available for AR-15 bolt carrier groups (BCGs). Each has its own unique characteristics including color which ranges from silver to gold to black and various shades of each. Let's compa …

Toolcraft makes bolt carrier groups (BCGs) in a variety of finishes and calibers but probably none have captured the imagination like their Nickel Boron (NiB) BCGs. Let's take a look at 'em!Basics Remain the SameA Toolcraft Nickel Boron BCG will start out as a solid chunk of specially blended 8620 Aircraft Quality steel. After machining and hardening and final machining all parts go out to be plated with Nickel Boron. Toolcraft uses UCT Coatings of Palm City FL for the Nickel Boron f …