The Cycle of Operation: What Actually Happens When You Press the Trigger

The AR-15 is a gas-operated, rotating-bolt rifle. The heart of the system is the direct-impingement gas path and the bolt carrier group (BCG). Think of the cycle in a clean sequence:

• Firing: The trigger breaks, the hammer drops, and the firing pin ignites the primer. Powder burns, pressure spikes, and the bullet begins its trip down the bore.
• Gas Tap: As the bullet passes the gas port, a portion of that pressure is siphoned through the gas block and down the gas tube into the carrier key.
• Unlock and Rearward Travel: Gas vents into the carrier, driving the carrier rearward. The cam pin rotates the bolt, unlocking it from the barrel extension. The extractor maintains control of the case as the carrier continues rearward, and the ejector kicks the casing clear.
• Buffer System: The carrier compresses the action spring via the buffer. That spring is your clock—too much gas or too little spring creates timing issues; balance is everything.
• Feed and Lock: The spring drives the BCG forward, stripping a fresh round from the magazine, chambering it, and locking the bolt lugs back into the extension. The rifle is back in battery.

When shooters talk about reliability, they’re really talking about this timing. Gas port size, barrel length, gas system length, buffer weight, and action spring condition all determine how violent or smooth that cycle feels.

Gas Systems: Carbine, Mid, Rifle—Why It Matters

Gas system length sets dwell time—the window between when the bullet passes the gas port and when it exits the muzzle. More dwell time means more gas volume and more impulse on the carrier. Carbine systems on 16-inch barrels can run “gassy,” which is fine for dirt tolerance but harder on parts. Mid-length smooths that out for most general-purpose builds. Rifle-length on 18–20 inches delivers the softest impulse and best parts life, provided your ammo and porting are correct.

Here at Taylor Defense, we advise matching the gas system to the mission. Suppressed rifles benefit from properly sized ports or an adjustable gas block to avoid over-speed. If you run a can often, an H2 or H3 buffer and a fresh action spring are smart choices to tame carrier velocity.

Bolt Carrier Group Basics: Where Reliability Lives

The BCG is the engine. Key points to watch:

• Gas Key: Tight, properly staked screws prevent gas leakage. Any wobble or carbon tracing here is a red flag.
• Bolt Lugs: Even wear and clean faces. Chips or peening mean it’s time to replace the bolt.
• Extractor System: Spring, insert, and O-ring (if needed). Weak extraction shows up first with steel-cased ammo or underpowered loads.
• Cam Pin and Firing Pin: Keep them clean, lightly lubricated, and inspected for cracks or deformation.

Lubrication matters. The AR-15 likes to run wet—especially on the rails of the carrier, cam pin, and bolt. Light oil on contact points beats a dry, gritty cycle every time.

Magazines and Ammunition: The Often-Ignored Variables

Most malfunctions aren’t mystical—they’re magazine or ammo related. Quality mags with good feed lips and strong springs fix more issues than exotic parts. When you’re chasing failures to feed, swap mags first, then test with known-good brass-cased ammo before you blame the gun.

Watch the full video above for detailed insights and demonstrations.

What to Watch for in the Video

As you watch, pay attention to the moment the cam pin rotates the bolt out of lock, the relationship between gas system length and carrier velocity, and how the buffer system arrests that motion. Visualizing the gas path from port to tube to carrier key will make your next cleaning session more intentional and your troubleshooting faster under pressure.

Additional Insights: Tuning, Maintenance, and Safety

There’s a reason professional users obsess over gas and timing. An over-gassed rifle beats up the bolt, extractor, and receiver extension. Symptoms include harsh recoil impulse, excessive ejection angle (forward of 3 o’clock), and premature parts wear. Solutions are straightforward: heavier buffer, stronger action spring, adjustable gas, or a correctly ported barrel.

Maintenance should be scheduled, not reactive. At Taylor Defense, we recommend:

• Daily/Range Session: Wipe carbon from the bolt tail and inside the carrier, relube generously, and check the gas key for looseness.
• Every 1,000–2,000 rounds: Replace the action spring if it has shortened beyond spec; inspect extractor springs and inserts.
• Every 5,000 rounds (use-dependent): Consider a new bolt, or at least MPI/HP-tested replacement if your gun sees hard use or high heat strings.

Safety is non-negotiable. Confirm clear before maintenance. Use a chamber flag on the line when appropriate. Keep the muzzle managed, finger off the trigger until sights are on target, and know your backstop. When diagnosing malfunctions, slow down: lock the bolt to the rear, strip the mag, and clear the chamber deliberately. Rushing creates new problems.

For suppressed setups, manage heat and fouling. Carbon builds quickly with a can, so stretch your lube schedule and consider a high-temp grease on bearing surfaces. Gloves and eye pro aren’t optional when you’re pulling a hot BCG from a suppressed gun.

Legal note: Verify your local regulations on barrel length, braces, suppressors, and parts swaps. Here at Taylor Defense, we keep our guidance aligned with current laws and best practices, and we encourage you to do the same.

Final Thoughts

The AR-15 earns its reputation because it’s predictable. Learn the cycle, respect the timing, and the platform will reward you with consistency. If your rifle talks—through ejection patterns, recoil impulse, or wear—it’s giving you data. Use it. If you want help diagnosing a persistent issue or just need a sanity check on gas and buffer choices, reach out. Taylor Defense is here to keep your carbine reliable, accurate, and mission-ready. Drop your questions below, share your range notes, and let’s keep the community sharp and squared away.