We decided to take a crack at building a .223/5.56MM Special Purpose Rifle style upper receiver for an AR15. We wanted to end up with an accurate rifle, low recoil impulse that is extremely shooter friendly.
Rather then go specialized tool crazy. we decided to minimize what we used to make the project easier to assemble. Brownells $99.99 AR-15/M16 Critical Tool kit provides most of the specialized tools we use here. The kit, consisting of an armorers wrench, lower receiver block, receiver action block, detent depressor, pivot pin installation tool an bolt catch pin punch provides a builder the essential rifle specific tools needed to work on their AR-15/M16.
To build this rifle (we already had a CMMG lower), we ordered the following items: (Note, we included the lower receiver parts and will be adding an article outlining complete assembly of the rifle in the near future.)
With our upper receiver complete, we grabbed a CMMG lower we had lying around. Installing a Magpul Gen-2 PRS stock and Geissele DMR trigger, the rifle was complete. To top the upper, we selected a Leupold Mark 4 2.5-8×36 M2 TMR scope in an ADM recon mount. Initial testing was quite positive, with three different loads coming in sub-MOA. A complete review will be following shortly.