Maxim Defense MXM47572 JP Silent Captured Spring 9mm Tungsten/Stainless Steel for AR-Platform

The Maxim Defense MXM47572 JP Silent Captured Spring for AR-platform rifles is a 9mm spring system engineered specifically for shooters running the Maxim Defense CQB Stock System. Built from tungsten and stainless steel, this captured spring assembly delivers the reliability and consistency you need in a short-stroking, quiet AR build—whether you're working a suppressed setup, running subsonic ammo, or testing a precision build at the range.

Unlike standard buffer tubes and springs, a captured spring system keeps all components contained within the assembly, eliminating rattle and simplifying maintenance. The 9mm-specific weight is tuned for the impulse characteristics of that cartridge, ensuring reliable cycling and consistent bolt lockup. Because it's manufactured exclusively for Maxim Defense, this spring pairs seamlessly with their CQB Stock System, giving you a cohesive, purpose-built platform.

Installation requires an open channel in your bolt carrier group to allow the guide rod full travel during firing. If you're building or upgrading an AR-9 with Maxim Defense components, verify that your BCG is compatible with captured spring systems before ordering. This is a precision part—fit matters.

Key Features

• 9mm-specific spring weight for reliable cycling in AR-9 platforms
• Tungsten and stainless steel construction for durability and weight management
• Captured spring design eliminates rattle and looseness
• Designed exclusively for Maxim Defense CQB Stock System
• Requires compatible bolt carrier group with open guide rod channel

Specifications

Frequently Asked Questions

Will this spring work with any AR-9 or do I need specific components?

This spring is manufactured exclusively for the Maxim Defense CQB Stock System. Your bolt carrier group must feature an open channel to allow the guide rod to pass during firing. Check your BCG compatibility before purchase.

What's the difference between this 9mm spring and a standard or heavy-weight option?

The 9mm-specific weight is tuned to the impulse and cycle rate of 9mm cartridges. Maxim Defense also offers standard/carbine and heavy-weight versions for different calibers and use cases—select the 9mm version for AR-9 builds.

Is this a complete buffer assembly or just the spring?

This is the JP Silent Captured Spring System designed to work with the Maxim Defense CQB Stock System as part of your upper receiver assembly. Verify compatibility with your current setup before ordering.