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

NCAA2026 Day1 1
NCAA2026 Day1 1

Ole Miss Makes History at NCAA Rifle Championship, Leads After Day One in Columbus

Ole Miss fires a program-record 2356 to win its first-ever NCAA team discipline title in smallbore. Kentucky’s Braden Peiser claims individual smallbore crown.

Review: Henning Group 2011 Grip

Henning Group’s new 2011 metal grip delivers improved recoil control, customizable textures and easy installation for Staccato, Springfield Prodigy and STI-pattern frames.

NRA America’s Rifle Challenge: Kyle Lamb’s Guide to Mounting a Scope for ARC

Kyle Lamb walks through optics mounting with practical advice on leveling, eye relief and preventing scope shift during ARC competition.

Politics, Weather and Rising Stars Mark a Turning Point: 1990 National Matches

The 1990 National Matches at Camp Perry saw funding threats, severe weather cancellations and major victories by shooters like David Tubb and Jim Meredith as a new decade began.

Review: GP Arms Patriot Rebel

The GP Arms Patriot Rebel is a mid-level 2011 built for Limited Optics, delivering 1,000-plus rounds of flawless reliability including a full USPSA Nationals.

Milan Cortina 2026: Team USA’s Masters Defends Paralympic Biathlon Title With Perfect Shooting

Oksana Masters defended her Paralympic biathlon sprint title with flawless shooting at Milan Cortina 2026, with teammate Kendall Gretsch taking silver.

Interests



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