JP Enterprises Silent Captured Spring Gen 2 (AR-10, Standard)

The JP Enterprises Silent Captured Spring Gen 2 for AR-10 (JPSCS2-10) replaces a large-frame AR's loose buffer and action spring with one self-contained assembly. The spring rides on a guide rod instead of scraping the inside of the receiver extension, which is what removes the spring twang and the gritty sound when the rifle is charged or fired. The buffer is captured on the same rod and travels with the carrier, so the assembly keeps the dead-blow buffer function that resists bolt carrier bounce.

This is the standard-mass AR-10 unit. It ships with three steel masses for 2.9 oz of buffer mass and JP's 10-110 spring, weighs 5.0 oz complete, and includes a spacer so the same unit runs in a carbine-length or rifle-length tube. JP designs it around the standard 7-inch carbine receiver extension used on DPMS-pattern .308 rifles such as the LR-308. Armalite's .308 carbines use a slightly longer, non-standard carbine tube; there the spacer has to be modified to fit, or the tube swapped for a standard 7-inch carbine extension. The spring is removable, and JP sells an AR-10 alternate spring pack for tuning.

JP's selection guide pairs the standard JPSCS2-10 with low-mass operating systems and an adjustable gas block, and sends short-barreled rifles, high back-pressure suppressor use, piston systems, and select-fire rifles to the heavier JPSCS2-10H2 or H3. Swapping the steel masses for JP tungsten weights raises buffer mass, which is JP's recommended fix for bolt bounce. Some proprietary carriers block the guide rod, including certain PWS carrier groups and the Daniel Defense DD5; JP states the SCS works with carriers whose rear bore is as small as .530 inch.