After drilling and routing, I've attempted to assemble the lowers... One minor problem:

The Jig allowed me to remove a tad too much material from the right rear of the receiver pocket. The result is the hole that houses the take down pin spring and detent was breached just enough for the detent to slip off the end of the spring and fall into the lower.

I can think of a few solutions:
1. Maybe a small diameter aluminum tube will fit the spring inside and still fit in the hole in the lower.
2. Glue (The challenge is gluing in a way that makes a hole, and not just a wider lower).
3. Solder (same challenge as above, plus I have to buy the stuff).

Any advice about materials to use, or suggested methods would be appreciated.

http://www.cavmfg.com/CAV-15-MKII-Take-Down-Pins-CAVTDP.htm



$10 shipped

I actually had that happen once and I found a small piece of wire that I scrounged up that was the right size, I put it in the hole and smeared some JB weld over it and let it set up, I coated the wire with wax before I did it and was able to fix it and as fare as I know that gun is still working just fine and that was 3 years ago.

I saw a YouTube video similar to what you said but instead of putting a,wire in the he JB welded it then drilled the hole again.

This is how I did it, it looked great. JB weld didn't hold.
I went with the new pin.

I have repaired several with that problem.  You just purchase 1/8" tubing (copper or brass) and drill out the existing hole with a 1/8" drill bit.  Cover the tubing with epoxy or jb weld and slide it in place. Trim to fit, and you are back in business. The internal diameter of the tubing is 3/32nd" which is the diameter of the the original hole.  I also tap the tube with a 4/40 tap and use a set screw with a shortened spring. I never have to  remove the pin after that.

I posted pictures in another thread years ago how to do it (I used a 5/32nd drill bit, and a roll pin to accomplish the same thing.  I even used the same process on a Flat Spot steel receiver and it worked fine. Here is the thread    Photobucket nuked the pics