NSR Pro - 14.7" 5.56 Pencil Barrel + Lightweight BCG - Complete Upper

The NSR Pro is our first and probably only lightweight build.  Coming in at just 54OZ (3lb 6oz) this is a true lightweight upper that still performs to a very high standard and doesn't shoot like a standard lightweight upper. Its excellent shooting performance comes from two factors, a lightweight BCG (8.9 OZ Complete) and an adjustable gas key from Rubber City Armory. The combination of low reciprocating mass and fine adjustments on the gas key means the NSR Pro is a very fast, very flat shooting upper receiver. Now this is not what I consider to be a duty or extreme use build as the lightened BCG and pencil barrel will not hold up as well to abuse and excessive thermal cycling. The point of this build is to maintain the highest level of performance in as light of a package as possible. Every component is still backed by our no questions asked lifetime warranty, and yes the first rebarrel is still free. 


*Alternate Muzzle Devices Available Upon Request At Dealer Cost - Includes FREE P&W*


The Basics


14.7" Ballistic Advantage Pencil Profile 5.56 1:7 Twist 4150 CMV Barrel, Breek Arms 13.7" Mlock Handguard, RTB Lightweight BCG, Rubber City Armory Adjustable Gas Key, Aero Precision Slick Upper, & Breek Warhammer Charging handle


Pinned Gas Block, Lapped Upper Receiver, Bedded Barrel, Every component is hand fitted and tested prior to assembly, test firing, and ultimately shipping. 


The Specifics



Manufacturer - Ballistic Advantage

Length/Chamber - 14.7" 5.56

Twist - 1:7 

Material - 4150 CMV

Profile - Pencil

Gas System - Mid-Length

Finish - Nitride

Thread Pitch - 1/2x28

Gas Port - .093

Weight - 21 oz

*Pinned Gas Block*

1st Rebarrel - FREE


I tested with several loads and was able to get good (1 MOA) performance out of HSM 77gr and Nosler 77gr ammo. I also was able to get this upper consistently out to 700 yards. 


All NFA/ATF Rules Apply


Barrel nut is sequentially torqued down to 50 FT-lbs. Starting at 25, then 35, and then finally 50 FT-lbs to ensure proper mating of the threads. 


Barrel is also bedded to the upper receiver with an expanding/hardening compound to ensure perfect fit and reliable accuracy. 


If you legit burn out a barrel, like 10,000 -25,000 rounds, and the barrel becomes inaccurate I will rebarrel it for you for free. Good luck.


Bolt Carrier Group:

Manufacturer - RTB (Most likely Odin Works is the OEM)

Bolt Material - 9310 Alloy

Carrier Material - 8620 Alloy

Gas Key Material - 4140 Alloy (Rubber City Armory Adjustable Gas Key)

Profile - Lightweight

Finish - Nitride

Gas Key Screws - Grade 8

Forward Assist Cuts

Mil-Spec Firing Pin (Hard Chrome Coated)

Viton O-Ring Enhanced Extraction



Manufacturer - Breek Arms RG2 Wedge Lock

Length - 13.7"

Material - 6061 T6 Aluminum

Finish - Hard Coat Black Anodization

Mounting Platform - Mlock

Barrel Nut - Steel


Barrel nut torqued to 50 FT-lbs

Handguard screws torqued to 60 IN-lbs with blue Loctite


We apply a Permatex Anti-Seize solution to the receiver extension before installing the barrel nut to ensure they do not lock up over many years of hard use. 


Upper Receiver:

Manufacturer - Aero Slick Side

Material - 7075 T6 Aluminum

Machined from Forged Aluminum

Finish - Type 3 Hardcoat Anodized Black

Standard Dust Cover

M4 Feed Ramps

T-Marked, if you care...


Charging Handle:

Manufacturer: Breek Arms Warhammer (ambi + gas busting)

Material: 7075 T6 Aluminum

Machined from Forged High Strength 7075 Aluminum

Finish - Type 3 Hardcoat Anodized


Gas Block:

Material - 4140 Steel

Style - Low Profile

Size - .625"

Attachment Method - 2x Set Screws + Steel Roll Pin

Not Adjustable


Set screws are torqued to 30 IN-lbs and have High-Temp threadlocker applied for extra security.


*Please contact me before attempting removal of the Gas Block. These are not meant to be tampered with. 


Gas Tube:

Length - Mid Length

Material - Stainless Steel


*** Any flash hider/ muzzle brake on the market can be substituted at dealer cost on your upper ***


Flash Hider:

Type - A2

Manufacturer - KAK

Thread Pitch - 1/2x28

Caliber - .223/5.56


The Build Process:


Every upper is assembled by me, one at a time. Every piece is hand fit, barrels to the uppers, gas blocks to the barrels, gas tubes to the blocks, handguards, roll pins. If something doesn't fit properly and securely, it doesn't get shipped out. What that means is that you get an upper that you can depend on and will hold up to years of hard use. 


On top of that we use the proper threadlocker on the appropriate parts. We use blue loctite on the handguard screws and then torque them to 60 IN-LBS. On the gas block screws we torque them to 30 IN-LBS then use a red high temp threadlocker (#272) to ensure the gas block never shifts. #272 threadlocker holds its strength up to 450 degrees VS. the 300 degrees of standard loctite.

NSR Pro - 14.7" 5.56 Pencil Barrel + Lightweight BCG - Complete Upper

  • Our stated policy is to not accept returns, but if you accidently ordered the wrong item or there was a mistake or if you have any issue at all send us an email (listed in the "contact us" section) and we will work it out.