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

2026 Southerngrand Teamfederal 1
2026 Southerngrand Teamfederal 1

Anderson Shares Singles Title After 450-Target Marathon at Southern Grand American

Weston Anderson and Ricky Marshall, Jr., declared Singles Co-Champions after breaking 450 consecutive targets at 2026 Southern Grand American.

Clay Blackketter Claims Open Division Title at 2026 Southern Iowa Showdown

Team Hornady’s Clay Blackketter wins Open division at 2026 Southern Iowa Showdown shooting A-Tip Match bullets.

Team Remington Dominates Junior, Veteran Divisions at 46th Southern Grand American

Team Remington captures two championship titles at the 46th Southern Grand American at Silver Dollar Shooters Club in Florida.

USA Shooting Junior Program Gets a Boost From MidwayUSA Foundation Lones Wigger Endowment Grant

A grant from the MidwayUSA Foundation’s Lones Wigger Endowment will cover ammunition, targets, entry fees and travel for USA Shooting’s junior athletes, including the 2026 ISSF Junior World Championship in Germany.

Your NRA In Your Pocket: Official App Now Available on iOS and Android

The NRA’s new official app offers a digital membership card, NRA-ILA news, digital magazines, local event search and exclusive member benefits on iOS and Android.

Historic Runs and Budget Storm Clouds: 1991 National Matches

The 1991 National Matches featured dominant performances by David Tubb Steve Reiter and Lones Wigger amid budget uncertainty and extreme weather.

Interests



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