hope this isn't too stupid of a question.  i've been considering it for a while- i'm one of those guys that likes to do EVERYTHING myself.  i know i'd have to somehow turn it down to half an inch and then get the appropriate tap and fluid.  i'm pretty handy- just thought i'd ask if anybody had done it and if by chance there was a writeup somewhere on it.  thanks.

You could, but you really need a lathe or some method of keeping the bore exactly centered to the thread and in the flash suppressor and cut perpendicular to the bore.  By the time you buy the dies, a tool to keep them alligned and square to the bore...you are going to be out several times the cost of having it threaded.  I had mine done for $25 from someone who was also doing other work for me, but even if you  paid the going rate of $45-$50, you are still going to be bucks ahead.  And if you do the work yourself without a lathe, and get things off center, you have damaged the barrel and if it is only a 16" barrel, no cutting it off and trying again unless you want to SBR it, and that is another $200.