Five grains does make that much difference, as well as type and brand sabot...

My Knight likes 80grs FFF Goex with the .430 Hornady in 300gr...My brother's Knight prefers 85 grains with the same powder and bullet and my hunting buddies prefers 85 as well...

I use to start at 100 and go down 10 grains when working up a load, now I start at 80 and move up...