Does FortuneCookie45LC know what he's talking about here?
Based only on my personal experience of over 50 years shooting revolvers, mostly S&W and Ruger, shooting cast and jacketed bullets, my considered opinion is he doesn't know jack...squat.
On the other hand, I
could be completely wrong, and his ideas might be just the ticket for a match revolver, or something like that, I don't know. What I do know is I've owned regular factory production revolvers that don't do what he says needs done, and they have shot somewhere between fine and outstanding by my standards.
I've read a lot about chamber throat sizes, forcing cone and bullet sizes, and what combinations were "best" long before the Internet and U tube existed. I find the information and the discussion interesting but largely irrelevant to me.
I don't know what my revolvers chamber throats measure, I've never measured them, and I feel no need to do so. I don't care if they meet some self appointed expert's idea of what is right, or best, I care about what they DO in my hands with the bullets I shoot, and so far all have been acceptably accurate for me.
he explains that the chamber opening (exit) should be .001 to .0015 smaller than the bullet diameter, and the forcing cone should swage the bullet another .001 to .0015, for a total of .002 to .003
I don't get this, either. By his standards, the cylinder should squeeze the bullet down and then the forcing cone do the same for a total of .002-003" smaller than original bullet diamter. SO, by his standards the .452" slug I'm shooting in my .45 Colt should be .450" or even .449" when it enters the barrel. Otherwise, my gun won't be accurate???
Against this (for one example) I've got a Ruger .45 Colt Blackhawk I just dropped a .452" 200gr JHP slug into each of the chambers and one chamber it falls straight through, and the other 5 it doesn't fall straight through but if you shake the cylinder a little bit, it falls right out. SO, no squeezing the bullet there.
Yet that same gun, in my hands will shoot a 2-2.5in group at 25yds and ring the 2ooyd gong on the rifle range regularly if I do my part correctly.
I would recommend not paying a who lot of attention to U Tube experts and focus on what the gun(s) and ammo in your hands does. IF yours does what the U Tube guy said it does, fine, he got it right. But if it doesn't?? Draw your own conclusions.