I gave my opinion about P.O Ackley and his tests here:
The basic problem with the Army running tests to "prove" they were not at fault, and P. O Ackley running tests to "prove" that blowing out the shoulders reduces bolt thrust, is that neither were an independent tester and they simply tested until they proved the point they wanted to make.
Ackley wanted to prove you could just pour on the coal and it was all OK because of the Ackley improved taper. While his cartridge taper test found a funny, it did not change the fact that the laws of physics remain the same. You increase combustion pressure you increase the stress on the action.
I have read anyone number of posts from people whose charge values hugely exceed that of reloading books, they claim, just like Ackley, from physical observations of sticking, bolt lift, primer condition, that everything is just fine. Physical observations are unreliable indications of combustion pressures.
I remember an article in the 90's, a pistol reloader was exceeding by a wide margin published data. His cases fell out of the cylinder, so he was theorizing that the more powder you put in, the less pressure you got. When his loads were pressure tested, they were above 80,000 psia.