CMMG 55CA9A2 AR15 Spring Action Stainless Steel - High-Performance Rifle Component

The CMMG 55CA9A2 AR15 spring action in stainless steel is a critical component for reliable carbine-length AR-15 builds. This stainless steel spring pairs with a carbine-style buffer to create the consistent spring force and resistance your rifle needs to cycle reliably across different ammunition loads and gas system configurations. Whether you're assembling a new carbine or upgrading an existing receiver extension, this spring delivers the performance balance that separates a solid shooter from one that runs rough.

Carbine-length buffer systems are the workhorse setup for AR-15s—compact, lighter, and faster-cycling than rifle-length alternatives. The spring in this system does the heavy lifting: it controls bolt carrier group speed, manages recoil impulse, and works with your buffer weight to keep everything running smoothly. Pair it with the right carbine buffer, install it into your carbine-length receiver extension, and you've got a platform that'll handle everything from subsonic hand-loads to full-power duty ammo without beating itself to death or short-stroking.

CMMG stainless steel springs resist corrosion and maintain their rate consistency over time—no rust creep, no mystery performance drift. That's especially valuable if your AR sees field use, rough storage, or humid climates. For builders dialing in a new carbine or gunsmiths stocking reliable OEM-quality parts, this spring is a straightforward, proven choice.

Key Features

• Stainless steel construction for corrosion resistance and durability
• Designed for carbine-length receiver extensions and buffer systems
• Provides reliable spring rate for consistent bolt carrier group cycling
• Compatible with carbine-length gas systems
• Works in tandem with carbine-style buffers for balanced operation

Frequently Asked Questions

What buffer do I pair with this CMMG AR15 spring?

This spring is designed to work with a carbine-style buffer. The weight and resistance of the spring-and-buffer combination together ensure reliable operation, so match spring and buffer as a system for best results.

Will this spring work in a rifle-length receiver extension?

No. This spring is designed specifically for carbine-length receiver extensions. Do not use it in a rifle-length setup.

What gas system length is this spring for?

This spring is engineered to work with carbine-length gas systems. The balance of spring rate and buffer weight is tuned to that configuration.

Is stainless steel worth the upgrade over standard spring steel?

Stainless steel resists rust and corrosion better than standard steel, which is valuable if your rifle sees field use, humid storage, or outdoor conditions. Standard springs will work fine in dry climates and controlled environments; stainless is peace of mind for long-term reliability.