Product Overview
JP Silent Captured Spring — Tuned for .338 ARC Subsonic & Reduced-Gas Setups
Make subsonic tuning forgiving and get reliable, smooth operation in reduced‑gas builds. The JP Silent Captured Spring for .338 ARC is a replacement, captured spring that keeps the carrier closing force close to stock while significantly lowering the gas force needed to open the bolt — an excellent choice for both subsonic and carefully tuned supersonic loads, especially on pistol‑length gas systems.
Key benefits
- Easier subsonic tuning — Lowers the gas force required to unlock, making suppressed/subsonic loads much more forgiving and reliable.
- Maintains carrier close force — Closes the carrier at 94% of the full‑strength spring, preserving reliable lockup and feeding.
- Reduced gas to open — Requires 18% less gas force to open the bolt versus a full‑strength spring — ideal for reduced‑gas or pistol‑length gas systems.
- Versatile — Works well with both subsonic and supersonic ammunition when you need to reduce gas flow to the action.
Technical summary
- Designed for: .338 ARC platforms
- Function: Captured, silent spring assembly tuned to reduce required bolt‑opening gas by ~18% while retaining ~94% carrier‑closing force of a full‑strength spring
- Best suited for: Suppressed/subsonic loads, pistol‑gas‑length systems, and builders tuning for reduced gas flow
Installation & notes
- Drop‑in design for straightforward installation; follow standard armorer safety and procedures.
- Tuning: Because this spring reduces the gas needed to open the bolt, verify gas port sizing and buffer/weight choices when switching between supersonic and subsonic loads.
- Compatibility: Intended for .338 ARC bolt/carrier assemblies — confirm fitment with your specific upper/bolt group before use.
Why choose this spring?
It provides the sweet spot many .338 ARC users need: near‑stock closing reliability with noticeably lower gas demand to unlock. If you’re building a suppressed subsonic rifle or trying to make a pistol‑gas‑length system run reliably with heavier bullets, this spring simplifies tuning and improves consistency across loads.
