JP Silent Captured Spring Pack - Small Frame AR15 / JP-5

JP Silent Captured Spring Auxiliary Spring Rate Kit (JPSCS)

The Auxiliary Spring Rate Kit for the JP Silent Captured Spring (JPSCS) allows precise tuning of your rifle’s operating system to match its specific configuration.

The factory-installed spring is designed to deliver optimal performance across a wide range of setups. However, by simply disassembling the unit and installing a different spring, you can achieve fine-tuned performance, especially on rifles without an adjustable gas block.

Spring Selection Guide

➤ Use a heavier spring if:

• You feel the buffer fully compressing and bottoming out during firing

➤ Use a lighter spring if:

• The bolt carrier does not reliably lock back on the last round
• The issue persists even when the rifle is fully gassed
• You are using an ambidextrous bolt catch extension (e.g., Magpul BAD Lever) and the bolt overrides the catch

💡 In this case, the combination of increased bolt speed and added mass on the bolt catch can prevent proper engagement.

Spring Identification (Lightest to Heaviest)

Kit Contents

• Full set of tuning springs
• One spare guide rod retainer screw (in case of thread wear or stripping)

Compatibility

Compatible with:

• JP Silent Captured Spring Gen 1
• JP Silent Captured Spring Gen 2 (AR-15 models)

Quick Rule of Thumb

• Bottoming out → use a heavier spring
• Failure to lock back → use a lighter spring