Originally Posted by
UncleNorby
We can only guess, but if the work was done by someone that knows what they are doing, I suspect the scope and/or scope mounts.
This^^^^
Something is loose or the scope is bad. I was on an elk hunt and stopped in to zero at elevation before the hunt. After a box of rounds, I was on my way to the small town to pay way to much for a scope but it fixed the problem. Scopes do go bad, especially if it is a cheaper brand of scope on a heavy recoiling rifle.