1. Set of Roll Pin Punches
2. Set of Roll Pin Holders. Expensive but well worth it. The pins prevent misalignment.
3. Brass/Nylon Hammer
4. Steele and Brass Punch Set
5. Gunsmith Block
6. Bench Vise
7. Quality Cleaning Kit. I prefer Otis Cleaning Kits.
8. Always remember the best tool of all is patience!!!!
For most of your specialty AR tools go to Brownell's at http://www.brownells.com/. I find the following tools the most useful when assembling lower receivers and working on uppers. For Brownell specific tools I've included their part numbers. These tools save you a lot of time.
1. Bolt Catch Pin Punch #080-216-012 (see picture above). The pin allows you to drive the bolt catch pin straight on.
2. Pivot Pin Detent Depressor #080-216-010
3. Pivot Pin Detent Installation Tool #080-216-011
4. AR Armorer's Wrench
5. AR Handguard Removal Tool
6. Lower Receiver Action Block for both the AR-15 and the AR-10
7. Upper Receiver Action Blocks for both the AR-15 and the AR-10