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Re peak time, a bullet traveling 1000 FPS would exit a 24" barrel in 2 milliseconds. Since this is from a dead start, if it accelerated linearly, it would take 4 ms. Since it accelerates faster at the beginning, it would be significantly less than 4. A high velocity rifle like a 220 Swift going 4000 FPS will take less than a millisecond to exit.
In a handgun with a 6" barrel at 1000 FPS, we are also talking about less than a millisecond for the whole event.
Of course, the peak will be shorter. There will be a period where pressure builds up before the bullet moves far. I have no idea what that is.
Bill
Just checked QuickLoad and calculates the pressure and velocity at various place as the bullet moves down the barrel. With the printed out graph a person could get good estimates of both at various barrel lengths. Just grabbed a 222 printout and it shows 3626 PSI initial pressure, probably before the bullet starts to move. Bullet travel at Pmax (45,827PSI) is 1.35 inches.
Just looking at the Q/L printout for 222 and peak pressure is at approximately .31ms (1.35 inches) bullet exits the barrel (22inches) at .976ms with a pressure of 7062PSI. I hope no one quoted this post yet. Less than a millisecond to exit the barrel is probably right. Abbreviation for microsecs is different.Another problem is that the pressure generation is transient, more like shock loading. Some metal behave differently between slow and rapid loading. I would question if the pressures are uniform.
The pressure peak is probably in the microsec range than millisec.
Tom
We have test ported a barrel every inch following the groove. Waiting for approval to release the data.
OK just checking out my knowledge from what I have read on this site and from following links posted on this site. I am not a gunsmith. First the pressure is the same on all inside walls of the cartridge. The amount of brass present in different areas of the case transfer different loads to the different parts of the chamber wall and the bolt face. The heavy brass at the base of the cartridge along with the grip of the cartridge to the chamber wall reduces the stress on the bolt face relative to the chamber walls. The defining factor for the chamber wall is the hoop stress calculation for the cartridge chamber pressure applied to the cartridge case and the chamber wall.
This is my basic understanding of the situation so let me know where I have things wrong.
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