I saw a guy at Knob Creek gun range with an AR he had converted to a bullpup. He took an OA 93, which has a chopped bolt carrier and the buffer above the upper receiver, put a 20 inch barrel on it, and designed the linkage, which he said was the really hard part. He is good with fiberglass, so he made the stock himself. He let me and my wife shoot a few rounds through it. Kinda awkward, but I could see it being handy in closer quarters if you got familiar enough with it. All the parts he didn't fabricate himself, other than the OA parts that I mentioned above, were generic AR.