MK1 - 11.5" 5.56 Complete Upper Receiver - Pinned Gas Block

The MK1 is the first upper in a series of custom uppers. Focusing on bringing the highest value and performance possible in an affordable way.


The Basics


11.5" Ballistic Advantage 5.56 Upper, 9.7" Breek Arms Mlock Rail, Toolcraft NIB BCG, Mil-Spec Upper and Charging handle


The Specifics



Manufacturer - Ballistic Advantage

Length/Chamber - 11.5" 5.56

Twist - 1:7 Twist

Material - 4150 Chrome Moly-Vanadium

Profile - Government

Gas System - Carbine

Finish - Nitride

Thread Pitch - 1/2x28

Gas Port - .072

Weight - 22oz


*Pinned Gas Block*

1st Rebarrel - FREE


All NFA/ATF Rules Apply


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


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 - Toolcraft

Bolt Material - 9310

Carrier Material - 8620 Alloy

Gas Key Material - 4130 Alloy

Profile - Full Auto

Finish - NIB

Gas Key Screws - Grade 8 (torqued and staked to Mil-Spec)

Forward Assist Cuts

Mil-Spec Firing Pin (Hard Chrome Coated)




Manufacturer - Breek Arms

Length - 9.7"

Material - 6061 T6 Aluminium

Finish - Hard Coat Black Anodization

Mounting Platform - Mlock

Barrel Nut - Steel (does not require timing)

Wedge Lock Attachment


Barrel nut torqued to 50 FT-lbs

Wedge Lock is tightened to 60 IN-lbs


Upper Receiver:

Manufacturer - Anderson

Material - 7075 T6 Aluminum

Machined from Forged Aluminum

Finish - Type 3 Hardcoat Anodized Black

Standard Forward Assist

Standard Dust Cover

M4 Feed Ramps

NOT T-Marked, if you care...


Charging Handle:

Material - 7075 T6

Machined from Forged Aluminium

Finish - Type 3 Hardcoat Anodized + Teflon Coated for Smoother Operation


Gas Block:

Material - 4140 Steel

Finish - Nitride

Style - Low Profile

Size - .750"

Attachment Method - 2x Set Screws

Not Adjustable



Set screws are torqued to 25 IN-lbs and have High-Temp threadlocker applied for extra security.



Gas Tube:

Length - Carbine

Material - Stainless Steel


Flash Hider:

Manufacturer - Breek Arms

Type - 3-Prong Flash Hider

Material - 4140 HT Steel

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, I don't put it together. What that means is that you get an upper where every component fits together like a glove for a rock solid build that won't fall apart or tear itself asunder during 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 35 IN-LBS. On the gas block screws we torque them to 25 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. 


MK1 - 11.5" 5.56 Complete Upper Receiver - Pinned Gas Block

  • 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.