What do you think about this one x serial number and no roll mark.

Fixed it for ya  Along with ALL of your other acquisitions, this one is also a fantastic find.  Lower receiver appears to be a very early A2 forging as the lines of the reinforced areas such as pivot pin and receiver extension are very "organic" as described by Augee in the Lower Guide sticky on top of this forum.  Like someone said in the other forum, this would be an easy lower to clone due to lack of roll-mark.  ETA: I was just wondering what if there's any marking on the barrel and what profile is underneath the hand-guards.

Nice I would like to see a picture of the right side of the lower.

Is this another one from Targetmaster's?  

I've gotta say, they get some interesting stuff there.

~Augee