I have a 223 that hates 55 gn bullets. Stick a 60 or heavier in her and all is well.
In theory it should only go up or down,but I have not found that to be the case in any of my rifles. It shifts to the left and right as well. From a 55 to a 70 is a very big difference in a 223. Your twist rate will also have a lot to do with it.
I have (only
) 9 rifles right now,but I used to chase different bullet weights around in each one. I had 3 different loads for my 223 ranging from 60 to 75 gn bullets. Then I just decided to get more rifles
. Now I have one load that shoots very very accurate out of each of my rifles. I sight them in on that load and never have to mess around again. The rifle I take with me depends on what I am going to be doing and the distance I want to shoot. Life is easy that way
My 223 with 60 gn is my Yote rifle out to around 400 to maybe 450 yards, After that It is a Yote that will live to see another day as I will not push my rifle ability or more important my ability to make a clean kill.
If it is your only rifle,make your loads and just write down on paper your scope settings for each load and have at it. As long as you have a good tracking scope you should be able to jump back and forth.