Last lot # change was 0.8 gr to get same velocity. Majority of the time, closer to 0.2 or 0.3 gr +/- but every now and again you see a larger variation. Largest variation I’ve seen was 1.5 gr to get same overall performance.
EVERY powder mfg’er, every version of powder they make shows this. I’ve learned there is no exception, start low and work up to verify burn rate of lot # being used.
If you just throw in same charge weight as last lot # and let rip, you are going to be pretty warm if not out right hot.
Where you are on pressure curve has huge influence also, pressure curve is not linear.
Loading manuals vary quite a bit, lot of variables.
Hence, one can not supply a recipe unless everything is exactly the same lot #, base to ogive is same, brass brand is same (you’d be surprised how many people change brass, don’t account for case capacity difference).
One can supply suggestions but not a recipe.
Load for a really wide variety of chambers, barrel mfg’ers and your view changes rapidly.