You know what I am trying to do? Make you mad? What if I wasn’t?
I thought you were trying to show off, barrel time, milliseconds, something like 1.5/100000.
Back to the 308W fired in the M1 30/06 chamber, when fired and the case forms to the body of the chamber the 30/06 shoulder is .382” ahead of the 308W shoulder, that is a drop in pressure and a a big delay for the bullet, I will admit you have the ‘hint of the beginning of a shoulder’ at the mouth of the formed 308W case fired in a 30/06 chamber down pat, but, when the barrel time and millisecond thing is applied to the neck of the 308W neck? The neck normally expands .010” + or – when the neck is supported, when the neck is not supported the neck disappears and becomes part of the case body, when the neck of the case becomes part of the case body the shoulder of the case does not have support and as a results the hot high pressure metal cutting gas is escaping around the bullet before it, being heavier and with an additional .350”+ jump to the lands, can reach the rifling, so case expansion causes pressure to drop, gas escaping past the bullet causes a drop in pressure, and again when the neck expands and become part of the case body the bullet is left, almost, unsupported.
And I am sure if they were using a spacer they would have told you, backing the 308W ammo against the clip to get started and holding the ammo there is something that had to be worked out when 308W barrels were installed on the M1. Again, it is a mistake and or a bad habit to fire 308W in a 30/06 chamber, I want my cases to cover all of the chamber possible, all that hot high pressure metal cutting gas can not be doing the exposed area of the chamber any good.