So, I had gotten the idea to order a MechTech upper for my RIA 1911 10mm, to use during my states handgun deer hunting season. Then it hit me, with an attached stock it would be classified as a long gun, so no go. Then I got to thinking, what if I ordered an upper with the M4 style stock and replaced it with a SB47 brace? I am wondering if I modifying the upper would be kosher. It is only considered as a barrel attachment and I think I would be on strong ground if I modified it. I will not take anything posted as legal advise, I am simply looking for some members opinions.

Legally, the brace is not a butt-stock, so that could work. The barrel length may be a problem, though. Check the maximum length of a "handgun" in your state. It may also have an overall length limit. As far as the game warden is concerned, the only serial number on the weapon should be of the 1911 frame. If it meets the other criteria, the only difference, if he runs the serial number, may be the barrel length and "color" of your 1911 handgun. However, he could be an Adam Henry about it and seize it until it's defined in court. Be on your best behavior, and have handy a copy of BATFE's latest letter regarding the brace. If neither of you are an Adam Henry at the time, there should be no problem.

I would call your local fish and game office and ask them.  Or read your states laws regarding handgun hunts.  They should have information there that will guide you in the right direction.