.416 Rigby and Somchem powders ?

Hello,
I will be assisting a good friend of mine in Namibia set up his reloading kit on my next visit. After doing some research it appears that the only powders that will be available to us in Namibia are Somchem. I am sure they are of excellent quality but reloading data is hard to come by. I have been able to find data on some of the more common calibers but not 416 Rigby.
By looking at burn rate charts it appears that S 385 is the closest to Alliant RE22 which is what I use here in the states with 410gr bullets. Any information that could be provided about the 416 Rigby with S 385 or any other Somchem powder for that matter would be greatly appreciated. I understand that all rifles are different and any information posted may not be safe in my rifle.
Thanks,
Dirtdart

I use to reload my 416 Rigby with Somchem S385 and S365 i still do have all the data and will gladly send you the info as given to me by Somchem.
Johan