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

1A Mauser M98
1A Mauser M98

New Mauser M98 Das Original Bolt-Action Rifle Includes .300 Win. Mag. Chambering

Mauser updates its classic M98 with DLC bolt components, Grade 5 wood and new calibers including a first-ever .300 Win. Mag. option.

Winter Olympic Biathlon: Skiing and Shooting at 180 BPM

A history of Olympic biathlon, tracing its evolution from military patrols to a high-speed sport combining skiing and precision shooting under pressure.

New For 2026: Top Handguns

Eleven standout handguns—from race-ready steel to modular pistols and a modern revolver—highlight the biggest trends emerging from SHOT Show 2026.

New: Real Avid Master Collection for 1911

The 1911 Master Collection brings together tools, cleaning gear and chemicals in a single kit designed for straightforward at‑home maintenance of the classic handgun platform.

Collegiate Rifle: 2026 Patriot Rifle Conference Championship Results

Nebraska secures 2026 PRC Championship title in Fort Wayne with balanced scoring in both guns, topping Ole Miss and TCU for its first league title in two decades.

Kim Rhode Receives NSSF’s Top Honor at SHOT Show 2026

Olympic legend Kim Rhode is honored by NSSF for a career that reshaped competitive shooting and expanded its future.

Interests



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