For a while now, I’ve been using some Real Avid brand specialty AR tools that I now consider indispensable for any AR build project. The first is their LUG LOK Upper Vise Block for barrel installation and removal. This tool engages the bolt lugs in the barrel extension and prevents torque from being transferred to the sides of the upper receiver. This tool retails around $60. The second is their Smart Fit AR15 Vise Block, which can be tightened in the magazine well to hold any lower still while you work. MSRP is about $30. The final item is less than ten bucks but worth far more than that in hassle. Their AR-15 pivot pin tool makes that job a snap.

The other tools you’ll need you may already own: a vise mounted heavily enough to hold steady under torque up to 80 lbs. for mounting the barrel and holding the magazine well vise block, forceps to hold you pins while you tap them in place, large high quality Vise-Grip pliers with their jaw tips shielded with tape, roll pin punches and small hammer, an armorer’s block or a piece of wood to support the rifle when you install pins, a ½” drive torque wrench, a barrel nut wrench, a large blade flat screwdriver to attach the buttstock, some graphite free grease to keep the barrel nut and receiver threads from galling (Aeroshell 66 is recommended), and a roll of thick duct tape to protect the receiver when you are installing pins. Finally, get a headspace GO and NO-GO gauge too. I got mine from Brownells for $66. AR parts are so precisely made these days, I know some folks who think nothing of putting a rifle together and using only a live round as a headspace gauge. Don’t do that. It’s unwise at best and unsafe at worst.