I have now an 80% lowers - fortunately I got them a couple of years ago, and got them cheap.

I tried using the big (1&1/16) drill bit, and messed up the alignment.  Pretty annoying, because I had already ton a lot of work on it.

Maybe it would go better with some vises in the drill press, except my drill press is not big enough, so I swung the top around.

I tried the reamer, but it does not appear to cut well enough.  I found a web site where the reamer was tapered, but I have no idea how to do that, any suggestions?

thank you

Richard

Find a local welding shop and have them run a bead of aluminum wire weld in the buffer tube hole and start over.

Ideally there should be a fixture which locates off the takedown pin holes which has replaceable drill bushings.

1 size to ream the tap drill size
1 size to act as a tap guide.

I used a boring head (in a Bridgeport Knee mill) to be sure hole was both proper size and position.

80%'s can be completed with just a drill press and hand tools, but require supporting fixtures to get it right.

Richard..

just JB weld the buffer tube on permanetly.... should work just fine.