Corey there are certain rules that are like certain old "horse and buggy laws". OBSOLETE. IMO using WW in conicals is one of those obsolete ideas. I believe it had a place over 100 or 200 years ago when soft steel was used for barrels. But with todays modern barrels I think it is just a "Wife's Tale".
I have been shooting WW in conicals and lead round balls for years with absolutley no problem.
The only real difference is that slightly harder lead will cast at a slightly larger size than what pure lead willl cast. But we are talking .001's or less. So a properly sized bullet for your bore is drastically more imprtant than the actual alloy of the lead.
I would bet a dollar to a donut that if you have your bullets sized properly, you will notice absolutely zero difference between WW and pure lead. Just my opinion. Tom.