I took this off a early mid 90's preban lower that I bought used. Upper forge code is EK. Cast FSB is roll pinned instead of the usual taper pins. Unmarked Hbar 20" barrel with a nice bore. I measured the twist with the cleaning rod method and came up with 1-9". Based on what I'm seeing I think it has NO chrome lining. Not sure if its 5.56 or .223 chambered either. There are NO markings on barrel. A2 guards with no heat shields. Nice finish overall, showing just a few handling marks and edge wear from the last 20 or so years. It came with a chrome lined Smith Enterprises BCG installed. The gas key is not staked at all. Just like the other SE BCG's that I have had. Carrier is clean but the bolt tail shows a little light pitting from improper carbon removal/maintenance. Noting major but worth mentioning and I can take pic if needed. I had an upper just like this a while back except it was in C7 configuration. Both of these uppers were installed on Preban Essential Arms A1 lowers. And both came with the SE BCG's. I posted AR15.com a while back and the consensus was its an Oly, DPMS, Early Bushy, Model 1 or a Nesard parts kit upper. In other words there was no consensus and its still a mystery upper. I know these A2 uppers are wanted/needed these days so I figured I would list it here. I have this cross posted on other forums so first I'll take it gets it. $280 for upper with no BCG. $360 shipped for upper and SE BCG shipped via UPS ground insured only where legal. If the upper buyer does not want the the BCG I will sell the BCG separately. First dibs on the BCG goes to the upper buyer, if they do not want the BCG I will offer for sale here. USPS money orders only please. Feel free to ask any questions...I'm sure I missed something.