I have a Colt A2 upper that is marked with a C AF. I went to change the barrel and come to find out the little grove where the barrel tit slides into has been cut too wide. There is a lot of play in the barrel from side to side. Anybody else had this problem or come across this? I am going to try to put a wedge in it and see if it shoots straight. What should I do if this dosen't work?

Have seen this problem, and not just w/Colts. It can be caused by over tightening the barrel nut, which will cause the locating pin to dig into the left side of the slot and widen it. When I've encountered the problem I've simply cut a small piece of feeler guage, just wide enough to fit the slot and  pin snugly, put it on the left side of the slot (if the slot has indeed been widened by overtightening) and assemble.

If the over width is caused by just being too wide in manufacture, it'll be a tossup as to which side should be filled. If you have the ability to determine proper front sight base positioning, try shimming each side to see where the front sight is straight up and centered in the rear aperture, when the rear is in center position. You might even have to shim both sides.

I first put the barrel on and test fired it. I was shooting at 50 yards.  The rifle shot off to the right. Which would be consistent with the barrel canting to the left. It took 20 clicks of windage to correct it. I am going to try to wedge it to the right all the way and see what happens.

Problem fixed!
I used solder. I took a small bit pounded it with a hammer till flat. Then slid it in on the left side of the barrel tit and the upper. Well went to the range to test fire it and success, 4 clicks of left windage.

Good thinking on the solder[:D].  May try it myself if I encounter the problem again.

Looks like you had the same old problem I've seen posted here often before. Front sight base tilted to the left by a slot too wide on the left side. Rifle shoots to the right. New Bushmaster owners were posting on this quite a bit a couple of years ago; having to send the rifles back for adjustment.  Haven't seen any recent posts tho, so maybe they got their overzealous assembler(s) trained[:D]