Not much more I can add to this topic, other than to say that every belt I've built was done using Tandy blanks. And, like Andy, I was dismayed when my first blanks arrived and they were 1/8" less than advertised. 
But, I built the belts anyway and learned there's a reason!  Like rdb says, thinning a belt to make it fit a buckle is hard, unnecessary work. 
Alex