Most Popular Bolt Carrier Group for AR-15 / AR-10 / AR-9 / AK Builds in 2026

.308 Win vs. 6.5 Creedmoor for AR-10 Builds

A technical comparison of .308 Winchester and 6.5 Creedmoor for AR-10 platform builds — covering ballistics, recoil, parts availability, and which cartridge fits which use case.

5 min read

AR-10 Receiver Patterns: DPMS vs. Armalite Compatibility

The AR-10 has two incompatible receiver patterns — DPMS and Armalite — that look similar but do not share parts. This guide explains the differences and how to buy correctly.

6 min read

The AR-10 Platform: What It Is and How It Differs from the AR-15

A practical overview of the AR-10 — its origins, how it differs from the AR-15, available calibers, and when it makes more sense than a standard AR-15 build.

6 min read

AR-15 Caliber Options Beyond 5.56: What Changes and Why

A neutral overview of common AR-15 caliber paths beyond 5.56, including .300 Blackout, 6.5 Grendel, and .22 LR conversion approaches with practical system tradeoffs.

4 min read

AR-15 Catastrophic Failures: What They Are and How to Prevent Them

A guide to the failure modes that can injure a shooter (case head separation, out-of-battery detonations, squib loads, and gas key failure) with the specific conditions that cause each and how to prevent them.

16 min read

AR-15 Components: A Complete Reference Guide

A comprehensive overview of every major component in an AR-15 build—including what's inside bolt carrier groups and parts kits—organized by assembly for new builders.

12 min read

AR-15 Headspace: What It Is, How to Check It, and Why It Matters

Headspace is the one AR-15 measurement with direct safety implications. It covers what it measures, how go and no-go gauges work, and exactly when verification is required.

7 min read

AR-15 Malfunction Diagnosis: Reading What Your Rifle Is Telling You

A systematic guide to diagnosing AR-15 malfunctions (failure to feed, failure to extract, failure to eject, and double feeds) with root causes and how to isolate them.

7 min read

AR-15 Terminology: A Builder's Reference

A concise reference guide to AR-15 terms, acronyms, and concepts — covering the platform, components, ammunition, and legal classifications commonly encountered by builders.

10 min read

AR-9 Buffer Weights, Springs, and Bolt Velocity

How buffer weight, spring rate, and bolt mass affect recoil, ejection, and reliability in blowback AR-9 builds.

4 min read

The AR-9 Platform: Pistol Caliber Carbines on the AR Pattern

An overview of the AR-9 — what it is, how it differs from an AR-15, why builders choose it, and what to know before starting a pistol caliber carbine build.

7 min read

AR-15 Bolt Carrier Groups: Materials, Coatings, and Weight

A practical guide to AR-15 BCG tradeoffs, including bolt materials, carrier finishes, gas key quality, and how carrier mass influences system behavior.

6 min read