Purchased a clean Unertl at a gun show, dropped it on a rifle and off to the range. Unable to get a zero windage adjustment as i ran out od thread. upon checking, there is a boss cast into the sight of about .180 on the windage side, None of my other Unertls have this. Does this have a purpose and can I just mill the boss off the base?  Picattached

I noticed quite a big space in that slot in the upper right corner of the back mount. Also that screw in the upper right hand corner can be adjusted to have each click of adjust to also be the same amount. 
If you the ability to put the barrel in a vice and without damaging it. You can then typically take a dial indicator with a magnetic base. Place it on the back of the vice and dead center on both the top and then onto the side of Then adjust that screw to the point of the vertical and horizontal clicks are now being the same for each. Go say 20 or more the should go back right back to where you started from and do that several times to insure it repeats. 
I could be wrong but looking at that gap you are possibly loosing allot of the actual more than capable adjustments.
If you do a search on this site you should be able to find pictures of my setup for doing this.

One Unertl, when adjusting left would bottom out early on the spring loaded plunger at lower left of the ring and so would not go  "all the way" left and down.
Solution: I clipped a ring off the plunger spring. It works fine, now
beltfed/arnie

Sorry but that is not true. The Vulture does in fact have a 1" tube, that is for both the internal and the external. I went and measured mine to make sure. Unertl did make their external scopes with, 3/4", 7/8"and 1" diameter main tubes. 
Without actually seeing the scope and mount it is kind of hard to say just what the problem might be. I would guess it is quite possible that the mount is not origional to the scope or maybe its just a bad mount. 
Sam

Before altering the scope I would set the rifle up in a vice back off on the windage adjustment screw far as it will go. Then measure the tubes total possible  movement with a dial indicator, see what the range is. Back to dialed into your rifles windage settings & check were correct wind adjustment falls in the tubes movement range.

Without measuring most likely problem base position on the rifle or way the mount tightens to the base. You could test by installing another scope on the rifle & see how it zeros.

Problem with the way the mount is built very unlikely 

Boats

Could it possibly be that a base or both bases or not correctly drilled and tapped as being dead center to the barrel..

Steve Earl has bases that are not drilled for the install screws if you happen to have the means to drill them off center and to cut the screw head recesses yourself. Now that I understand what your problem is I have also run into this once one someone's rifle. I was able to use a shim on the rear base to get the scope closer to being re-centered in the mount. The problem  in that instance ended being that the base / bases were not centered with the barrel.

Saratoga Bill,
I think that if you were to loosen the clamp screw on the ring   
then move the windage assembly Left/deeper into its 
"hole", say until the "0" mark is almost at the boss, you 
will gain about two revolutions Left as in about 25 minutes.
Just be careful to keep the elevation assembly in its place 
if your elevation range is satisfactory.
You may want to unscrew and remove the spring loaded plunger on the lower left of the ring while you are doing this to make it easier.
beltfed/arnie