The stocks for CVA, and now Traditions, arms are made from some sort of "select european hardwood", probably beech. It is a clear grained easily machined wood. However, it is not very hard or dense. When tang screw is screwed down hard the wood compresses between the tang and the trigger plate, and doesn't leave enough room for the trigger to set.
Quick and dirty fix is to cut spacers from an old credit card and insert between the stock and trigger plate. Usually takes only one thickness, but sometimes two. When you find the right combination use just a bit of adhesive to hold the shims in place.
And just run tang and lock screws down to barely snug.