My reloading experience is limited. There is debate (from what I read) on uncompressed loads, whether they are forward or rearward in the case at the time of the shot as to velocity and other variables. Too technical for me ;D So by that theory compressed would be better in my mind. As far as compression goes in my loads it's minor. I can feel the bullet touch the powder and feel it compress but I think we're talking thousandths in depth. I run 25.3 H335 on my 55s 24.5 Varget on my 69s 44.5 Varget on my 175s and 46 Varget on my 150s.