Preview: JP Variable Mass Operating System

by
posted on October 19, 2016
** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. **
vmos-a.jpg
JP Enterprises new Variable Mass Operating System (VMOS) bolt carrier enables rifles to be easily tuned for a wider range of applications, such as suppressed rifles or exotic calibers.

"There's no such thing as 'one size fits all' in AR operating systems," states JP founder John Paul. "Tuning your rifle is the only way to realize its potential and provide the performance you want. That's why we pioneered the adjustable gas block concept more than two decades ago. Tuning can be the difference between reliable function and reliable frustration."
null
JP says, "The VMOS bolt carrier ensures reliable function, especially for systems without an adjustable gas block."

Like JP's other carriers, the VMOS models increase bearing surface. The cocking pad is longer, and exterior bearing surfaces are polished before the carrier undergoes a multi-vendor QPQ (Quench-Polish-Quench) process.

The VMOS is available now for large-frame (.308) AR-type rifles starting at $319.95. This standard version of the large-frame VMOS carrier includes three steel weights. Two weights can be exchanged for heavier tungsten ones. JP plans to release a small frame (.223) version early next year.

Latest

Rem Wethepeople America250 Jun2026 1
Rem Wethepeople America250 Jun2026 1

Remington We the People 250th Anniversary Ammo Ships to Retailers

Remington’s We the People 250th Anniversary ammunition is now shipping nationwide, a 2026-only commemorative run across rifle, handgun, rimfire and shotshell loads.

Kansas and Texas Headline Team Titles at 2026 4-H Shooting Sports Nationals

Kansas and Texas each claimed two team titles at the 2026 4-H Shooting Sports National Championships, which drew nearly 700 competitors to Nebraska.

XS Sights Adds Pre-Drilled Fiber Optic Sights for Smith & Wesson Revolvers

XS Sights now offers pre-drilled fiber optic sights for Smith & Wesson J-, K- and L-frame revolvers, installable without custom gunsmithing.

NRA Youth Ambassador Jackson Schmidt’s Bianchi Cup Experience

NRA Youth Ambassador Jackson Schmidt shares his first Bianchi Cup International Pistol Tournament, where he won Junior Rimfire division and placed third in Junior Centerfire.

Review: Vortex Strike Eagle 1-10X 24 mm FFP

A review of the Vortex Strike Eagle 1-10X 24 mm optic, a first focal plane LPVO built for multigun and IPSC Rifle competition.

Remington Performance Wheelgun 22 Rimfire Built for Classic Revolvers

Remington’s Performance Wheelgun 22 rimfire load is shipping nationwide, a 39-grain subsonic .22 LR cartridge built for classic revolvers and plinking.

Interests



Get the best of Shooting Sports USA delivered to your inbox.