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

F Class Lead 3
F Class Lead 3

NRA Introduces Three New F-Class Competition Categories for 2026

The NRA adds three new F-Class categories—F-Production, F-Precision/Any Rifle and F-Limited—to expand participation and modernize competition without altering traditional divisions.

NRA AR-Tactical Mid-Range Prone Is No Longer Provisional, Has a New Look

After a decade of testing, NRA approves AR-Tactical Mid-Range Prone as a full High Power discipline, adds two rifle categories and simplifies rules.

Review: Ruger RXM Pistol

Ruger’s RXM blends Glock Gen3 compatibility, Magpul modularity and solid range performance at a price aimed squarely at competitors.

John Moses Browning: Test Your Knowledge of an American Firearms Legend

Test your knowledge of John Moses Browning’s life and lasting impact with this fun 10-question quiz on America’s greatest firearms designer.

New: Taurus TX9

Taurus debuts the TX9, a modular, optics-ready 9 mm pistol family billed to deliver duty-grade reliability for everyday carry and competition.

The Quiet Discipline of Breath and Hold in Rifle Shooting

Explore how breath and hold control work together to reduce movement, reveal natural steadiness and guide the shooter to the perfect moment.

Interests



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