Quote Originally Posted by cranebird View Post
Thanks Gary. I might have stumbled onto something for you. http://www.6mmbr.com/223rem.html . Notice the PMP case listing in the .223 Rem case weight VS. Capacity chart . It is the heaviest case weight listed.It probably will take more powder than what the round is loaded at to properly fire form to the Ackley improved case dimensions.
Be careful with this, heavier cases generally have less water grain capacity and need the charge reduced by an equivalent percentage, otherwise its like adding that percentage difference to the lighter cases in their load.

Hope this doesn't confuse you. I've worked with many wildcat cartridges over the last 40+ years and if the shoulder will hold the round for proper headspace, I usually load a bottom end load for forming. If the case isn't in contact with the chamber allowing me to support it during fire forming, I will use the extended bullet trick, but with loads reduced by about 10 to 15 percent. Sometimes the case will not completely fill out the shoulder in those circumstances, and if that is the case, I will load it again, with a bottom end of the chart load to complete fire forming. I also usually anneal the case neck and shoulder before fire forming. Jim