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

ARC America 2026 2
ARC America 2026 2

NRA Launches ‘ARC Across America National Challenge’ for Nation’s 250th Anniversary

NRA’s new ARC Across America National Challenge runs Memorial Day through Labor Day 2026, aiming for 250-plus clubs hosting matches with national rankings and prizes to mark the nation’s semiquincentennial.

How Two Champion Skeet Shooters Launched Backwoods Suppressors

Olympic skeet medalists Vincent Hancock and Conner Prince co-founded Backwoods Suppressors, a hunter-first brand offering five titanium and stainless cans built for the field.

Kim Rowe Captures 2026 NRA National High Power Mid-Range Championship

Kim Rowe wins 2026 NRA National High Power Mid-Range Championship and Patriot Minuteman Trophy with a 2399-171X aggregate.

Federal’s 6.5 Creedmoor +Peak Adds 300 FPS to a Cartridge You Probably Already Shoot

Federal’s 6.5 Creedmoor +Peak uses Peak Alloy cases to push velocities 300 fps faster while fitting existing 6.5 Creedmoor rifles.

AMU Competitors Top 2026 Dixie Match Leaderboard

USAMU swept the podium at the 2026 Dixie Matches in Jacksonville, with Greg Markowski claiming Top Gun and the NRA Regional Championship.

The Whistler Boy Match Returns to NRA Smallbore

Sponsored by Ruger, the popular junior rifle competition is coming back in July during the 2026 NRA Smallbore Rifle Nationals at Cardinal Center in Ohio.

Interests



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