A case(221FB) that holds about 20 grains is not a fair comparison to a case(243AI) that will hold double or more...
Any "AI" case is meant to run hard and fasted than standard cartridges with case full of proper rifle powder,mostly on the slow side at that. It's in the man's book..
P.O.Ackley was an frontiersman and smart builder
I've got both of Ackle's books, and don't remember seeing anything like this.
Can you tell me which book he wrote this in? Was it book 1, or book 2?
Respects,
Richard