I picked up a no name scope mount at a show last week and I finally got a chance to mount it.  It mounts on the side rail using 3 hex head screws.

I put on top a red dot scope that I picked up at Bass Pro a few years ago (the red dot was previously on a .22 that I used for squirrel).

Set up at 25 yds and after 10-15 shots I got it hitting where I was aiming.

Put up a new target and backer paper on the OSB target stand and went back to 100 yds.

Fired 5 shots and looked through the spotting scope, nothing.  Walked out to look, nothing.

To make a longer story shorter, I had full down elevation dialed in, I ended up aiming at the bottom edge of the wood and I was hitting about 2 inches (yes that is right) from the top.  

I strapped the rifle in a cleaning vise and leveled the barrel.  I then checked the level of the scope and found it to be angled down in front.

The scope had integral mounts so I can't shim the back up to adjust, the mount is fairly hefty so I don't think I can "tweek" it any.

So that leaves me with repositioning the mount rail on the receiver. Can that be done?  I work on aircraft so riveting is no biggy, just wondering about if this is my only solution or am I missing something.

So your rail is probably about 1/4" lower at one end than the other?
It can be done; I had a smith actually weld mine and parkerize my SAR2. The build it yourself forum guys can give you more help on how to approach the rail job.