I took the plunge and built one too! I own a preban Polytech so I had something to go by. Never built one before in my life...I bought a Bulgarian milled receiver kit (wood stock) and Arsenal Bulgaria milled receiver from a guy who decided that it was too much to handle. The milled receiver barrel was threaded into the part of the old receiver, so I had to press the rear sight block off in order to unscrew the barrel. This was probably the most difficult task of the whole build, as I had to machine a special jig to fit around the block, as there isn't much shoulder to press on. What a pain in the ass! Once that was done though, I was able to unscrew the barrel and chuck it in a lathe even with the front sight still on. I turned the threads off and allowed .002" for the press fit into the new receiver. I pressed the rear sight block back on and then pressed the barrel into the receiver. The barrel has a shoulder on it, unlike the stamped receiver barrel, so I pressed in to the shoulder. Had to make another jig for this part... You need to make sure the front sight is lined up square with the receiver so it won't be canted. Headspacing checked out, so I drilled a hole through the receiver and part of the barrel and installed a barrel pin to mechanically lock the barrel in place, something I learned here. Once the barrel is installed the rest is simply bolting the stock and grip on to the receiver, installing the top and bottom handguards and installing the internals, bolt/carrier, recoil spring and top cover. I had to file the top cover a little because the selector would not quite close in the safe position. Actually before I installed the wood I cold blued the whole thing and it turned out like a new gun. It really made a difference in the appearance. Test fired flawless! The barrel installation is the only pain in the ass part of the whole build but I would do it again. I am lucky in that I have access to a machine shop so I was able to do the whole job by myself. You kinda learn as you go and you can always consult with the guys here; they helped me out with a couple of my questions. Good luck with your project!