THE A5
BUFFER SYSTEM
Developed at the request of the United States Marine Corps, the A5 is an intermediate-length buffer system that delivers the smooth, reliable cycling of a rifle-length action in a collapsible-stock package.
The heart of the "M16A5" concept — a solution that existed early, now matching the demands of modern operating conditions. USMC testing confirmed increased parts longevity over both the M4 carbine and M16A2 systems.
HOW THE A5 WORKS
Three components working as a system to fundamentally improve how the AR-15 cycles. Click any component to learn more.
CHOOSE YOUR BUFFER
Five weight options to match your gas system, barrel length, and suppressor setup. Each buffer has 4 internal weights — the "H" number indicates how many are tungsten (heavier) vs. steel (lighter). H0 = all steel, H4 = all tungsten. Start with the A5H2 if you're unsure.
A5H2
A5 Buffer — 5.3 oz
$48
The standard A5 weight and the recommended starting point for most builds. Ships with the complete A5 kit. Works with 14.5"–16" barrels in both carbine and mid-length gas.
Best For
Weight
5.3 oz
Internal Weights
2 Tungsten, 2 Steel
Material
Aluminum
Design
Deadblow
COMPLETE YOUR A5 SYSTEM
The A5 buffer requires a longer receiver extension and rifle-length spring to function. A standard carbine tube is too short — the buffer will over-travel and damage your lower receiver. Don't mix and match.
WHY A5 NOW
The A5 system has existed for years. What changed is the operating environment. Modern rifles are increasingly running conditions that expose the limitations of standard carbine buffer systems.
The A5 was designed early, but it solves problems that are now widespread. It's not a new solution — it's a proven one that matches current demands.
HIGHER PRESSURE AMMO
Modern 5.56 loads run hotter than ever. Standard carbine systems have a narrower margin for increased pressure. The A5's longer stroke and rifle spring absorb the additional energy, keeping the system within safe operating parameters.
SUPPRESSOR PROLIFERATION
Suppressors increase back pressure, which over-gases carbine systems — accelerating wear, increasing bolt speed, and creating harsh recoil. The A5 controls bolt speed across both suppressed and unsuppressed configurations without gas block adjustments.
SHORTER GAS SYSTEMS
SBRs and short-barreled pistols with carbine-length gas are inherently over-gassed. The A5's heavier buffer options (H3, H4) bring these aggressive systems into a reliable, controllable operating window.
OEM ADOPTION
Manufacturers like Sons of Liberty Gun Works ship rifles with A5 systems standard. The industry is validating what the USMC testing showed years ago — the A5 is a system-level improvement, not an accessory.
CARBINE vs. A5
The A5 is not just a longer buffer. It's a system — spring, buffer, and extension working together to change how the rifle cycles.
| Characteristic | Standard Carbine | A5 System |
|---|---|---|
| Buffer Length | Short (3.25") | 3/4" longer — more mass distribution |
| Spring Type | Carbine spring | Rifle-length spring — more coils, linear compression |
| Cyclic Rate | Faster, less controlled | Slower, more controlled |
| Bolt Carrier Velocity | Higher — more component stress | Lower — longer parts life |
| Dwell Time | Shorter | Increased — better extraction and feeding |
| Recoil Impulse | Abrupt | Smoother, more controlled push |
| Operating Window | Narrow — sensitive to gas, ammo, suppressor | Wide — consistent across variables |
| Suppressor Compatibility | Often requires gas adjustments | Handles both suppressed/unsuppressed |
| Stock Positions | 4 positions | 7 positions |
COMMON QUESTIONS
"ISN'T IT JUST A LONGER BUFFER?"
No. The A5 is a system: spring + buffer + receiver extension, designed to work together. A longer buffer alone doesn't change the spring rate, stroke length, or compression curve. The rifle-length spring is what provides the linear deceleration. The longer extension is what gives the bolt carrier the additional travel distance. All three components work together to change the timing and energy management of the action.
"IS IT ONLY FOR SUPPRESSED GUNS?"
No. The A5 improves both suppressed and unsuppressed performance. Suppressors amplify the benefits because they increase back pressure — but the smoother recoil impulse, reduced bolt velocity, and wider operating window benefit every configuration. Many shooters run A5 systems on unsuppressed rifles specifically for the improved feel and reliability.
"MY CARBINE RUNS FINE — WHY CHANGE?"
A standard carbine system may run reliably under controlled conditions with consistent ammo. The A5 expands the margin. It handles mixed ammo lots, temperature extremes, fouled conditions, and suppressor use with greater consistency. It also reduces component wear over time by lowering bolt carrier velocity. The question isn't whether your carbine runs — it's how wide your reliability margin is.
"IS IT PROPRIETARY FOR NO REASON?"
The A5 dimensions exist because they solve specific mechanical problems. The receiver extension is longer to allow more bolt carrier travel. The buffer is longer to house an additional tungsten weight. A standard carbine spring won't work because it doesn't provide enough return force in the longer tube. Every dimension serves a function — there's nothing arbitrary about the specification.
BUFFER WEIGHT SELECTION
Match your A5 buffer weight to your gas system length, barrel length, and whether you run a suppressor. When in doubt, start with the A5H2 and adjust from there.
| Configuration | Gas System | Barrel | Suppressed? | Recommended Buffer |
|---|---|---|---|---|
| Competition / tuned low-gas | Mid-length | 14.5"–16" | Yes (tuned) | H0 |
| General purpose, lightly gassed | Mid-length | 16" | No | H1 |
| Most versatile (start here) | Carbine / Mid | 14.5"–16" | Either | H2 |
| Over-gassed / suppressed | Carbine | 10.3"–14.5" | Yes | H3 |
| Suppressed SBR / heavy over-gas | Carbine | 10.3"–11.5" | Yes | H4 |
TECHNICAL RESOURCES
Learn more about the engineering behind the A5 system.
RE-A5 RECEIVER EXTENSION
The RE-A5 is the backbone of the system — a 7-position mil-spec receiver extension machined from impact-extruded 7075-T6 aluminum with a hard anodized finish. It accepts any standard mil-spec collapsible stock.
COMPATIBILITY WARNING
The RE-A5 is not compatible with standard carbine buffers or carbine springs. Using a carbine buffer in the A5 tube will cause the shorter buffer to over-travel, which can result in firearm damage. Always use A5-specific buffers and a rifle-length spring.
COMPLETE A5 KIT INCLUDES
- RE-A5 Receiver Extension (7-position)
- A5H2 Buffer (5.3 oz — standard weight)
- Rifle-length action spring
- VLTOR endplate & castle nut
UPGRADE YOUR PLATFORM
Ready to experience the difference? Browse our A5 components or reach out to our dealer program for volume pricing.