QuickLoad question

[normmatzen]

I need some factual data.
I just started a new lot of Varget. So, in an attempt to find out how I should change my load to account for a "little" difference in this batch compared to my last batch, I shot two each 5 shot groups, two with old Varget and two with new, both same load. The old lot yielded an average of 2931.5 fps with an sd of 2.8 fps and the new lot averaged 2977 fps with a sd of 5.45. For data, the groups at 600 yd were 3.25" for the old Varget and 3.5" with the new Varget, both over a MagnetoSpeed.
By simple ratio of the two speeds referred to load shows the new Varget should be 32.78gr. By fiddling with the QL Heat of Explosion ( QL number is 4050) gave me 4030 for the old Varget and 4120 for the new lot. This worked out to 32.7 gr for the same Mv as the old Varget.
My question is, what powder parameter should I be twiddling to account for the difference in the two lots?
The ratio solution and the Heat of Explosion both gave essentially the same load, so I feel OK. I just would like to find what changes lot to lot with Varget?

 

[Sheldon N]

My understanding is that the preferred method is to adjust the Burning Rate Factor (Ba) to fine tune results to match measured velocity, or to adjust for powder lot to lot differences.

That's what I've always done.

 

[jepp2]

You may find this useful.

 

[retired]

i play with
kj/kg