Stock makers order the bedding blocks from vendors with CNC equipment. I have found slight discrepancies in how they are machined out of spec, this makes for warping the action to conform to the bedding block.
To complicate things even more, actions often warp a tad during heat treat, some more than others.
If you look to shoot less than 1/2" groups, best to bed the rifle, float the barrel before you ever pull the trigger.
Stocky's has some of the best stocks with bedding blocks that I have ever seen, so has Accurate Innovations.