What I read from Tim's post was that when he fired std. 30-30 cases in the .30-30 AI chamber he lost 300 FPS. I could see that happening. I've always been under the impression that one of the features of the AI chamberings is that is that they CAN be fired with std. ammo if need be. Not that you'd want to but in case of an emergence and you didn't have any more AI cases at least you could still safely shoot the gun.
Also that the reason for increasing the size of the case is so that you can build as much or more pressure but the extra space allows the pressure curve to be a little more gentle.
Maybe it's my misconception. someone correct me if I'm wrong.
Sorry to back track a bit..
YES you CAN shoot factory ammo in a Ackley Improved cartridge. BUT, as Tim has pointed out there is a cost and its velocity/energy. I look at it exactly as you wrote it, in the event of emergency and to fire form cases. To my mind, to look at it as a detriment is short sited. The practice is perfectly safe.
The pressures are the same for both the AI and the STD 30-30. I think Krochus is confusing you. He is saying that the 30-30 is of older design and damn near the same improvements can be achieved by sinply loading the STD 30-30 to higher pressures. I know he is correct but loading beyond advertised pressure levels is treading on dangerous grounds. Pressure curves for the two cases is something none of us has the equipment to measure. Its been a long long timer since I read Ackleys book and flatly don't remember if what your saying is true or not. Anyhow, improving the case as in the AI design, you get a more voluminous case, allowing more powder to be utilized while maintaining the same pressures. More powder is more velocity and energy.
I hope that's more understandable...
CW
