Hello ! I am new to this site,and i was hoping to find people who might be able to get me started in the right direction.What I have is a custom built 416 rem mag. There is a very interesting story behind this rifle as to why it was built and why i have it.This is a very beautiful rifle and lots of fun to shoot.I have yet to slug the barrel to give me a starting point.I would also like to use the Greenhill Formula to help me find the perfect cast bullet for my rifle.I knowing that no two rifles of the same cal. shoot the same with the same load.I was wondering if anyone on this forum has done what i would like to do? this way i would have a very good head start with this 416 cal. I have found that RCBS makes a 350gr.fn,gc mold. I would like to be able to shoot a 500gr. or close to that with accuracy.Thanks for your help. darin