NBS Premium Series 11.5″ 5.56 Upper Assembly w/ Geissele MK4 Handguard

Built on a top tier 7075 forged upper receiver and fitted with the popular 11.5″ Modern Series Carbine Nitride Barrel from Ballistic Advantage, this premium barreled upper assembly is both durable and accurate. Over the years we’ve gotten thousands of 5 star reviews on the NBS line of complete uppers, we’re sure that this premium variant will go fast.

About the Handguard

The Super Modular Rail (SMR) MK4 M-LOK is Geissele’s ultra-lightweight M-LOK option. These rails are purpose-built and feature integrated M1913 picatinny rail sections at the fore of the rail in the 3, 6 and 9 o’clock positions. Maximum venting for heat dissipation also dramatically reduces the rail’s overall weight, while maintaining its same strong and rigid platform. Utilizing Magpul’s M-LOK technology at the 3, 6, and 9 o’clock positions, as well as the upper 45 quadrants. The SMR MK4 is both versatile and modular, allowing the user to tailor their platform to his or her unique needs.

The SMR MK4 also features Geissele’s proprietary 2.25″ long barrel nut. This increases the surface contact where the rail interfaces with the receiver and creates a platform that can be trusted to be straight and true the entire length of the free float rail. This increases accuracy and zero repeatability during disassembly and reassembly when performing maintenance.

Barrel Information

Over the years Ballistic Advantage has earned a reputation for quality. We’ve sold thousands upon thousands of these barrels and get nearly universal praise from our customers. This Modern Series barrel is chambered in 5.56 NATO which will accept both .223 and 5.56 NATO rounds. It has a 1:7 twist rate and carbine gas system. These barrels also have a very clean QPQ Nitride finish which which can extend barrel life well past 20,000 rounds depending on ammo and usage.

Build Quality 

All NBS uppers are 100% made in the USA assembled by experienced, hard working armorers according to modern best practices. No shortcuts are taken and we guarantee a fit and finish that will satisfy even the most discerning builder.