When I got my 28 nosler I loaded according to factory length. 3.340 found a load and it shot great. Started playing with seating depth. Grouping spread real fast and it seemed recoil increased. The assumption of .020 to .050 is just that. My 28 nosler is just one example. Of the 7 rifles I have or still reload for none of them shot well with the bullet stretched out. I dont know why. I've had way better luck staying close to reloading info length recommendations. However maybe I'm doing something wrong.