I use Hornady or Federal ammo only. Find the bullet that works best and stick with it. I've put alot off different factory fodder thru the chrony, believe me you can't handload better with average difference in velocity than Hornady and Federal coming in at maybe 12fps difference, with the max sprad being around 25fps.
I've put Rem. &Win Premium stuff thru and com up with varience being close to 125 fps. The difference in getting 3/16th groups or 1 1/4" ones