Lift for big shells

[Arthur]

I know several rules of thumb, 1oz/Lb up to 10Lbs the half an ounce per pound seems to be a fair one which falls down at the small sizes. However I want to put lift under a 16" ball shell weighing in at 17kilos (say 36Lbs) and this has to be right first time.

Have you ever made a working 16 about this weight? How much lift should I use. What grade of powder would you use?

[Mumbles]

That's a pretty light 16" shell. This was actually just being discussed on passfire. The oz per pound rule was based on the old goex, which is apparantly much stronger than current commercial powder. Others have recommended using 3/4oz or a full oz after 10lbs. Going a little extra never hurts anyway, especially considering that rule of thumb is made for canisters anyway.