Ackley was a snake oil salesman. His pseudo science tests allowed him to claim that his cartridges were superior to every other wildcatter out there. There were a bunch of attention seeking snake oil salesman selling their cartridge designs back then. Weatherby's claim was that the double venturi shoulders of his cartridge gave it extra speed, Ackley claimed that you could safely add powder because straightening the shoulder walls somehow decreased bolt thrust. The extra velocity these attention seekers achieved, was not by any design characteristic they created, the ultra high velocities they achieved were the result of insanely high pressures.
I remember a post somewhere, where a reloader had used Ackley's reloading data for one of his AI cartridges, and the post said "
you could reprime the case with a shot gun primer". That's how Ackley did it, insanely high pressures.
Ackley did not invent case friction. Case friction existed before Ackley. I have had stuck cases that I have had to knock out with a cleaning rod, so case friction still happens. Boatwright, a Mechanical Professor, in his blog
"The Well Guided Bullet" under mechanical studies,
http://www.thewellguidedbullet.com/pdfs/YieldingofBrassCaseWallsintheChamber.pdf discusses how case sidewalls stick to the chamber walls around 13,000 psia, and then start to stretch in the range 13-25,000 psia. If you notice, Ackley's 30-30 test does not have pressure data. Might have been a 10,000 psia test, just low enough that the case stuck in the chamber and did not blow the case head off. He might have also done something to the case and chamber. Tellingly, he did not test one of his 30-06AI cartridges, which in Handloader #1, Ackley claimed "normally" operated at 65,000 cup. That was when the 30-06 was a NTE 50,000 cup, and proof test loads were 70,000 cup. If Ackley had tried the same trick with a high pressure cartridge, the case head would have blown off. Maybe he did, but decided not to report it.
Handloader recently published a partial reprint of Handloader #1 and there was an article by Ackley on his 30-06 AI, but of critical interest, was a picture. In the picture was Ackley's pressure gage, and Ackley's bolt thrust gage. Just where is Ackley's bolt thrust data? I have never seen it, if you have it, how about releasing it? I am certain Ackley tested his ideas that AI cases reduced bolt thrust, in his bolt thrust gauge and found it false. And then, because that was, and still is a one of his major claims to fame, Ackley deep sixed the data.
So, by how much do you weaken an action, assuming the case carries some of the load? What is that number? How do you maintain it?