A few questions.
1) Why did you pierce the stamping? you could have just made radii at the end of the depressions.
2) Why did you add a weldment in the ejection port? You could just make the OD of the tube smaller, round down the edge and put the ejection port back.
3) You are trying to fit a steel stamping to an aluminum forging/machining, why are you trying to get perfect aesthetics? You are going to have to make it either very heavy or very expensive to achieve that.
In order to make a stamped anything you are going to have to make some rather complicated dies and you aren't going to fold it in one pass, even your first posted design would require at least two pressings, more likely three.
If you were planning for people to make the dies as well as do the folding, then machining the whole upper out of a square block of aluminum would be less work for the individual 'garage' (and would require less machines). If you were planning to supply the dies and have them do the pressing, yes a simple dies would be beneficial, but pressing just a round shape is more difficult than it seems and beyond most people garage abilities (It's not like bending a rectangular channel like an AK receiver). If you were planning to supply pre-pressed parts, then a complicated dies is of no consequence, as you only need make one set of dies.
I don't mean to rain on your parade, or poo-poo your ideas, but do you have any experience pressing anything beyond a simple rectangular channel (AK receiver)?