Speak to me about this.
Details?
TM sells lowers less the FCG pocket and a couple holes. There are jigs you can use to finish these on a drill press or mill or you can lay them out by hand/DRO and do them without the jigs. There is a bunch of information on cncguns.com
I like the Tactical Machining stuff a lot but if I'm going with an 80% I'm going to track down a yellow logic. Lowers are simple enough though, I could bang one out of barstock at work or home if it really came down to it.