So I mount a set of Talley lightwieghts on one of my Rem. 700's. I mount them & see that they are WAY out of alignment (up & down), according to my Wheeler Ring lapping tool. I screwed up & lapped a couple of rough spots off, before I noticed the height difference wouldnt be cured by lapping, therefore cannot return them.

What can I do? Is there something I can use to shim the front Base to sit higher?
I know someone else could have ended up with these & not knowing the difference would have likely just mounted them, the difference is about a 1/2 a dimes width. Should/Could I just use them anyways? or would this cause to much stress on the tube?

Get your self some steel shim stock in different thickness and shim away, should be fine.
You could send the rifle back to Remington and have them change out the reciever.

I always check the rings with centering bars before a scope goes in them.

Brownells sells shims, but "a half a dime's width" sounds like a lot to me. It's a quick job to cut down the base if you have access to a mill.
-Don

I have read somewhere that Remimgton changed their reciever demensions a while back, may have had something to do with the anti bind notch cut in the bolt lug. You might have an older reciever???

Just might need a different base. I think it was the rear demension, but cannot remember for sure.

If I did use a "half a dimes" worth of shims, I would want to incrrease the length of the screws as well.