AR15 Bolt Carrier Group Coatings & Finishes - The Good & Bad

Published on February 27, 2023
Duration: 25:18

This video provides an expert analysis of AR-15 Bolt Carrier Group (BCG) coatings and finishes, ranking them based on mechanical efficiency and dimensional accuracy. Chrome and Phosphate are highlighted for efficiency, while DLC and Nitride offer cost-effectiveness but can have dimensional issues. Nickel Boron is identified as the least favorite due to potential headspace and wear problems.

Quick Summary

Nickel Boron (NiB) is the least favored AR15 BCG finish due to common issues like short headspace, reduced firing pin protrusion, and fouling accumulation that can turn the BCG into a lapping tool, wearing down the receiver.

Chapters

  1. 00:00Introduction to BCG Finishes
  2. 00:53Chrome Finishes and Mechanical Efficiency
  3. 06:06Phosphate and NP3 Coatings
  4. 11:33DLC, Nano, and Nitride Treatments
  5. 16:06PVD and Aesthetic Coatings
  6. 17:52Nickel Boron (NiB) Issues

Frequently Asked Questions

What are the best AR15 BCG finishes for mechanical efficiency?

Based on extensive inspection, Chrome and NP3 finishes are generally associated with high mechanical efficiency in AR15 BCGs. Phosphate finishes, especially when chrome-lined internally, also perform well by holding lubricant effectively.

Why is Nickel Boron (NiB) considered a poor BCG finish?

Nickel Boron is often problematic due to coating thickness causing short headspace, reduced firing pin protrusion, and its tendency to trap fouling, leading to excessive wear on the receiver and BCG.

What issues can arise from Nitride BCG treatments?

Nitride is a surface treatment, not a coating, so it doesn't add thickness. Manufacturers may fail to adjust machining dimensions, leading to oversized bores, gas leaks, and potential brittleness in 9310 steel bolts if heat treatment is improper.

How does a BCG's finish affect its efficiency?

A BCG's finish impacts efficiency by affecting its sealing capabilities and friction. Smooth, dimensionally accurate finishes like Chrome or NP3 ensure better gas sealing and reduced friction, preventing cycling failures under non-ideal conditions.

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