Being a reletive newcomer to casting, about 8 years, I'm continually learning new things about this "arcane" art. Somewhere along the way I missed this subject. The reason I'm asking is as follows, I've read several replys to questions on BHN for air cooled and water dropped boolits made from WW. Most have noted the air cooled were in the 10 to 12 range while water dropped would be as high as 18 or more. I always kinda wondered about these figures because when I checked the ones I water dropped they would come out between 13 and 14 BHN. These were checked probably no more than a week after casting. Well, today I checked several boolits that I had cast last year and lo and behold they were a little over 20! So evidently there must be some "aging" involved here. This may explain some of the issues I've been having with lower pressure loads in my 45 colt. Maybe. Anyway, no more water dropped for me.