Re: wildcat on the 6.5x55 round?
dealing with the 6.5x55 case alone, P.O. Ackley did one as well as Dr. Arch. Very, very little difference between the two (if not identical). But I think the 6.5 Arch came around a little earlier than the Ackley case design. Then there is the 6.5 Vias which probably cannot be reamed off a standard 6.5 chamber without a barrel setback of a couple turns. Vias also did the same basic case in .224 and 6mm. They use a shoulder setback that is about .04" (could be slightly more as I don't have the drawings here). The .224 Vias will push an 80 grain bullet faster than a .220 Swift will push a 50 grain bullet! A 6mm Vias will push a 70 grain bullet faster than a .220 Swift will push a 45 grain bullet!
Ackley did the 7x57 Mauser case case in everything from .243" to .308", and others did the same case in .338 and 8mm. Fred Huntington also did some similar experiments, but with a 30 degree shoulder. I'd love to see somebody like Savage put their name on the .244 Rockchucker