Custom dies can get expensive
http://www.warner-tool.com/reloading.htm
http://www.neiljones.com/html/micro_dies.html
http://www.whiddengunworks.net/reloadingdies.html
This is picture of dies I posted on another site for a factory 30-378Wby custom 300Wby and 223AI
http://www.noslerreloading.com/viewt...hp?f=4&t=11615
This is picture of other Jones dies I use
http://www.noslerreloading.com/viewt...hp?f=4&t=11624 I started using these dies long before Redding and other started marketing bushing dies and here is set of neck dies I had made for a 223
http://www.noslerreloading.com/viewt...hp?f=4&t=11617.
Dies are just one part of accuracy and in a factory chambered rifle custom dies and be a hit or miss deal.
If you have 300mag and it's getting 1" groups how much wear do you want on that barrel trying to get smaller groups plus cost of the dies bullets etc.