While there may a little difference in results, using the recognised start load of 13gn Red Dot in cases larger than 30 cal is a good place to start. I cast for my 404 Jeffery and with a 400gn plain based boolit, used Red Dot for my subsonic load. This powder is not position sensative and starting at 13gn for 1096fps, I graduated to 14.5 for 1161fps. Have you been on the http://castboolits.gunloads.com/ forums. There is a wealth of knowledge there.

Von Gruff.