AR15 Upper Receiver Group Series – Part 1

Welcome to Part 1 of the 3 part series in which I show you how I assembled a new Upper Receiver Group for my AR15. The series will examine the tools used, the design choices I made, the build process, and my thoughts on the project.


I’m not a gunsmith, professional gun fighter, or all that mechanically inclined. I’m your average Canadian by day and an avid shooter and firearms enthusiast in my spare time.

AR15 Parts

Most of the parts laid out

Why build an new upper? Mostly for fun. I could have bought a whole new AR, or a factory assembled Upper Receiver Group for about the same cost as it was for me to assemble my own. I saw this as a chance to apply what I’ve learned that I like and dislike with my AR and learn more about how the parts work together to make a functioning firearm.

My first AR15 was the C7A1, the Canadian version of the M16, built by Diemaco/Colt Canada. But I’m not going to count that one as it belonged to the Crown and was just on loan to me. The first AR I bought was a Stag Model 2, which I have owned for a little over two years. The Model 2 is a 16″ carbine with an A4 Flattop. Over two years I’ve changed the furniture, tried a few sighting systems, and found aspects I like and dislike about the platform and that particular configuration.

I will be using this upper with an existing lower receiver group. This new AR15 will be used primarily for Close Quarter Battle (CQB) service conditions events with the Ontario Rifle Association (ORA). The CQB matches are held at CFB Borden, and engagement distance is from 10-35 yards.  For my new upper I have decided to use a Canadian made upper receiver with an 11.5 inch barrel, an 11 inch forward rail, and I’ll be mounting a 1-4 power optic.

Legal Issues

Canadian firearms owners will know that all AR15’s are restricted by name. Restricted firearms are usually handguns or short barreled versions of restricted rifles or shotguns. Restricted firearms can only be used at an approved range and cannot be used for hunting.

Most American states allow firearms owners with the appropriate tax stamp to own a Short Barreled Rifle, or SBR, a rifle with a barrel length of less then 16 inches. Canada does not have a similar law. In Canada most rifles are non restricted, unless they are semi-automatic and; have a barrel less than 470mm, or an overall length less than 660mm. All AR15’s are restricted by name, so all that is needed is a restricted endorsement on the owner’s firearms license. There is no tax stamp, or extra process. For Canadians wanting to buy an AR15 the process is the same as buying a pistol.


I have purchased most of my firearms specific tools through Brownells. Below is the list of tools I specifically bought for assembling AR15’s like in this project. Some of them, like the soft jaws, may have uses in other projects in the future.  I also had some other tools that I had purchased for other projects that I used with this project, like a brass/nylon hammer and bar clamps.

Tool Brownells Part # Manufacturer Cost
Roll Pin Punch Kit 230-112-105 Mayhew Steel $19.99
Receiver Blocks 080-000-659WB Brownells $65.15
Channeled Soft Jaws 100-003-410WB Wagner Industries Inc $39.99
Armorers Wrench 851-000-068WB Smith Enterprises $46.05


Acquiring the parts for the upper assembly build took about three and a half months. I was not in a rush to build the new upper receiver group, so I was able to wait for parts to come back in stock, and also to purchase items during sales. Some parts availability and selection was scare due to the panic buying in the US after the shooting in Newtown, CT. While some Canadians may have bought more than normal, we did not see the panic buying that took place in most of the US. We did see its results with retailers not being able to replace their regular inventory for much longer periods of time.

Being that I was building a fairly short carbine at 11.5″ I opted to put as long of a rail as possible over it to allow me to grasp as far forward as possible. After searching Canadian dealers and only finding a few over priced rails, I contacted Samson Mfg and dealt with their international orders department. I placed my order just before SHOT show and communication with them was great. The rail took about 10 weeks to be delivered.

Ordering from parts from Brownells is always an easy prospect. If the manufacturer is on the export list, and the parts are less then $100 no extra paper work is required. I ordered 3 roll pins in case I made a mistake during installation.

The Stag Model 2 I own has a very large muzzle break. It is loud and fun to shoot, but it does not seem to reduce felt recoil much compared to an A2 flash hider. Part of the CQB match is two rifle shoots to a target in quick succession. I wanted to find a muzzle device that would allow for fast follow up shots and selected Griffin Armament’s M4-SD II Tactical Compensator. The M4-SD II is 1.75″ in length bringing my total barrel length to 13.25″. The M4-SD II looks a lot like the Battlecomp and online reviews showed it to be a solid design while being about two thirds the price. It also came with a 2″x3″ moral patch, which was a nice bonus. Another unique concern with CQB is one stage is shot from the modified or urban prone. We must shoot laying on the ground using the strong side shoulder and the firearm must be kept off the ground. My Stag’s muzzle break tends to dig a hole in the ground and blow up a lot of dirt.

New Parts

Part Specs Manufacturer Retailer Cost
Receiver A3/A4 flat top Motiuk Mfg Motiuk Mfg $183
Barrel 11.5″, 1/7 , 41V50 steel,  Button rifled,  chrome bore and chamber Green Mountain Wolverine Supplies $249.99
Forend Evolution 11″ Samson Mfg Samson Mfg $159
QD Mount   Samson Mfg Samson Mfg $25
Roll Pin buy 3 DPMS  Brownells $0.99
Barrel Nut   Colt Brownells $15.94
Gas Tube carbine length  DPMS Brownells $12.27
Ejection Port Cover Engraved with Jolly Roger Harford Engraving Services Brownells $12.41
Charging Handle Medium  Bravo Company Machine Brownells $48.51
Muzzle Device M4-SD II Tactical Griffin Armament Armtac $94.99
Gas Block Low profile S&J Hardware S&J Hardware $49.99


Having previous experience with a number of red dot/holographic sights, and magnified optics, I’ve elected to use a 1-4 power optic. For CQB distances I could run irons, 1x red dot or a magnified optic. I used a red dot at some CQB matches last season with limited success. The dot was difficult to find in some lighting conditions, and there was no adjustment for the various distances. The scoring zones on the target are very small and the change in point of aim from 35 to 10 yards is significant. I’ve been very happy with the Vortex Viper PST on my precision rifle, and have purchased a Vortex Viper PST 1-4×24 specifically for this rifle and CQB.

Part Specs Manufacturer Retailer Cost
Viper PST  1-4×24 SFP EBR MRAD Vortex SFRC $549
Mount ADR 2″ Vortex SFRC $99

Recycled Parts

There is one part that I just could not source right now with out being gouged – the Bolt Carrier Group, or BCG. For now I’m borrowing the BCG from my 16″ Stag.

Part Specs Manufacturer
BCG Full Auto Stag Arms
Sling Vickers Combat Applications Blue Force Gear



For new parts this upper will cost $855, and another $650 in optics. Special tools, or new tools cost about $170. Some of the tools will be handy to loan to friends or for other projects.  At a future date I plan to assemble a new lower receiver group to mate with this new upper.

In Part 2 I will examine the assembly process and some of the parts in more detail.

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