Square forged vs. round forged upper

[Throatwarbler Mangrove]

So I'm working on a 603 clone, and I've secured a complete upper. It appears to be an older one with a C MP C-marked barrel with a forged/flashing milled off FSB. The barrel markings and FSB would date it at around 1969. The upper is a Colt with no forging codes and the VP and "C" inside a square in front of the ejection port area. But for the life of me, I can't tell if it is a square or round-forged upper. I've been comparing it to the best pictures on the web, and I just can't tell the difference. In some light angles, it looks square. In others, it almost looks round. Does anyone have any really good pictures of both for comparison?

[Throatwarbler Mangrove]

I figured it might be easier if I just showed pics of mine, and perhaps someone could tell me. It looks square to me, based on other pictures I've seen. But perhaps someone can tell me for certain. I've included a few pics of the FSB and barrel as well.























It isn't too big of a deal, but if the upper is square, then the barrel is a mismatch/rebarrel--albiet an early rebarrel.

[Throatwarbler Mangrove]

I'm bumping this one, because no one has been able to help; I'm hoping the right people just missed this post the first time.

[Kalahnikid]

I have an upper receiver that looks just like yours; judging from the left side I think yours (and mine) are round forge uppers but just barely.

The upper receiver forges were only good for a certain number of castings before they were too worn to be usable. They would have to be re-worked or replaced, so not all uppers are going to be exactly the same in terms of their lines. Square forge uppers were only used until 1966 (?) I believe, so certainly thousands of square forge uppers with a forward assist were produced, but round forge 603 uppers are were produced in far greater numbers.

[Renegade04]

Which 603 clone are you building? XM16E1 or M16A1?

[Throatwarbler Mangrove]

Renegade04, you can see pics of my complete build on post #216 (last page I think) of the Vintage AR subforum. It is an XM16E1. Kalahnikid, thanks so much for chiming in with your assessment! I just haven't seen enough of them to make a good comparison, so it is nice to have someone else speak up.

[Renegade04]

Took a look. Very nice. I did notice the items you pointed out. All in good time sir.

[MarkRSims]

Round Forge:
604later.jpg

Square Forge:
604early1.jpg