How much to back off depends on the cartridge size and the type of powder.Small cases like 223 a few tenths of a grain can make a big difference.In a larger case like a 300 Win Mag,.5grs or 1.0grs or more may be the amount you want to back off.The type of powder your using makes a big difference in the amount.Lets say the max load is 74.0grs of IMR 4350 and in the same rifle the max load was 79.0grs of Reloader 22.You would probably back off 1.0grs with the IMR 4350 and back off 1.5grs of the Reloader 22.These are just examples.

~Molɔ̀ːn Labé Skýla~
As Bob Hagel would say"You should not use a rifle that will kill an animal when everything goes right; you should use one that will do the job when everything goes wrong."Good words of wisdom...............