After week-long boondoggle of UPS mishandling my package, my lower parts kit finally arrived today.
I ran up to Harbor Freight to get some punches after arriving home. Apparently they do not carry roll pin punches at the North Austin location. I opted for a simple multi-size set of steel punches in black oxide finish (they also don't carry anything but a honking 5/8" punch in brass), along with a nylon/rubber mallet.
I had a hard time coming into this build figuring out exactly what I needed in the way of tools. Certainly there are armorer's sets for building an AR, but those are prohibitively expensive for the first-time builder. Here is what I have learned are the essentials for putting a lower together:
A Bolt Catch Punch
I learned this the hard way today, by ruining my bolt catch roll pin. If you look closely at the photo (you can click it to enlarge), you may be able to see the mangled end of my magazine catch roll pin slightly protruding from the rear of where it's supposed to be. This will have to be replaced with my next order of parts. An ordinary punch WILL NOT fit there, because the shank is centered in the punch, and the handle can't fit against the lower, parallel to the pin. These punches can be found from pretty much anyone who sells AR tools. Both Midway and Brownells have them available. The trigger guard roll pin is also the same diameter, so this punch can be used there as well.
A Nylon mallet
I picked one up from Harbor freight for about five dollars, but you can find them at all kinds of places, including Midway and Brownells. This is useful for using your punches, but also helps you finish off installing the trigger and hammer pins without marring the finish of your receiver and pins.
Specifically, 1/16, 3/32, and 1/8 inch sizes. While the 1/16 is not strictly necessary, It's nice for lining things up while you're working. The 3/32 is good for the trigger guard release, and the 1/8 can be used to get the mag release completely screwed in to the button.
Now, these are the things I found that were needed for a successful install. Here are the things I wish I'd had today:
A Vise and a Lower Receiver Vise Block
While you can put together your lower without these, there's only so many fingers you can use while holding the lower in your hand. A vise will keep you from making mistakes due to the distraction of holding the receiver. It will also allow more precise work. You can get a vise at any hardware store/mega home improvement mart. Vise blocks appear to be available from pretty much anywhere that sells AR tools, including Midway and Brownells.
A Pivot Pin Installation Tool
Installing the pivot pin spring and detent can be a pain, and one slip can send your detent flying across the room, never to be found again. I was able to avoid this fate with some finagling, but a purpose-built tool for this would have certainly sped things up and lowered the risk. Again, this can be found at places that sell AR tools, including Midway and Brownells.
So there you have it. My lower is mostly assembled, The buttstock (M4-style telescoping carbine) is already on order, and should arrive in about a week. Then, I move on to the expensive stuff. Everything besides the CMMG stripped lower is being assembled with parts ordered from Rock River Arms.
Thanks to aepilotjim and the rest of the folks from the GBC for their assistance in this endeavor. For a good guide to assembling your AR, check out the How To Build An AR-15 videos over at Brownells.