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

2 Cciblazer Clean Fire
2 Cciblazer Clean Fire

New: CCI Blazer Brass Clean-Fire Suppressor Ammo

CCI’s new Blazer Brass Clean-Fire Suppressor subsonic ammo uses lead-free components to reduce fouling in suppressed pistols and carbines.

What’s In Your Range Bag, Natalia Siek?

NCAA Division I rifle athlete Natalia Siek shares her journey from first perfect 10 to international competition, plus the gear and mindset driving her success.

Six New Competition-Ready Optics for the 2026 Season

Six new optics from SHOT Show 2026 designed for competitive shooters, featuring quality glass, improved reticles and versatile mounting options across platforms.

SHOT Show 2026: Staccato HD C4X

Staccato’s HD C4X pairs a 4-inch compensated barrel with an aluminum frame, aiming to balance duty-grade shootability and everyday concealment in a compact 2011.

Benelli Updates Montefeltro Silver Semi-Automatic Shotgun Lineup

Benelli updates the Montefeltro Silver semi-auto for 2026 with engraved nickel receivers, AA walnut furniture, Inertia-Driven action and Crio chokes in 12- and 20-gauge models.

Winchester’s USA 250th Anniversary Ammo Puts History in a Box

At SHOT Show 2026, Winchester displayed its USA 250th Anniversary Commemorative ammo boxes with archive art and theme-matched loads in a limited run of 15,000.



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