First off: this is not a difficult project. There's not much in the way of tools needed to turn an 80% lower into a ready to build lower receiver. In no particular order:
- Drill bits in 1/8, 5/32, 5/16 and 3/8"
- A decent set of calipers. Digital calipers are cheap nowadays.
- A bit of a trick here: either a drill press or a milling machine. There are many "Mill-drills" (example) on the market which can do this, but an 8" benchtop drill press (for example) will do. If you don't have a drill press, they are just so handy for any wood or metal working that, honestly, use any excuse you need to get one. I used my CNC Sherline because it's what I had - wouldn't you?
- An end mill: 3/8" is a common shank size, almost universal, and will work fine. A smaller mill takes longer to clean up the insides. I believe the largest you can use is 7/16". End mills are available in a center cutting styles, but won't be unless stated. An end mill is not a drill, but a center-cutting endmill works better for small amounts of drilling than the other kind. If you use a milling machine, you'll use an end mill holder or collet; on a drill, you'll use the drill's chuck.
- Most of the lower is 1.249 deep, but there's a "shelf" near the butt stock end that is 0.63" deep.
- The Colfax lower comes with a CD Rom that has several worthwhile drawings. You can find almost all of them online separately, but it's handy to have them in one place.
- A fixture: either the one Colfax Tactical sells or the one from CNC Guns. This clip, modified from the instructions will help.
It's easy, it's fun, and you end up with a rifle. What could be better? As always, you can email the blog account or comment here with other questions.