Glad you got it back and running!!! After running some rounds through it I bet the tuned spring will be fine, even tho I dont understand why a tuned spring is needed anyway.
You might want contact the company who did the work to see if they will do anything for you since they screwed up.
Did the gunsmith tell you how many test fire rounds they put through it?
I'm going to have go run hopefully 500-1000 rounds myself before it becomes my carry, because they didnt say how many rounds.
And the believed the tuned spring to be to light but I explained it was to make the gun reliable for everything including 147g subsonics (as per MOD-K over the phone to me)
And as for dealing with mod-k I'm not mad about it, I dont know who does their cerakote and things happen, I'm actually happy that it was to thick and not to thin of a layer.