A North Texas gun smith had a walk in customer with a rifle that was locked up; the shooter was going to sue everyone. He was going to sue the manufacturer of the rifle, the salesman that sold him the ammo, the manufacturer of the ammo and the salesman.
It took over 2 hours to get the bolt open. The case head was so flattened Remington 308W could not been seen on the case head. And then the smith asked to see the box of ammo and the receipt, it did not take him long to determine there was only one round missing from the box of 20. After the research he asked the shooter about the chamber in the rifle. The shooter insisted the rifle was a 308W. the smith then asked who owned the rifle.
The irate shooter claimed he volunteered to test the rifle for accuracy. It was at this time the smith informed the shooter he was one very luck man because the rifle with the stuck case was a 25/06 and he could forget suing anyone.
And then the guessing started; observers were betting on how long the bullet must have been when it left the barrel. I did not get involved because no one would believe how the 308W bullet got past the forcing cone.
It apparently takes a heavy hand and far end of tolerances to cram an 8mm into a .30.
And then there is the pinching of the neck you mentioned. It takes little effort and there is no way the end of the neck of the 8mm57 can get pinched when chambered in a 30/06 chamber unless we are talking about Bart B's firing pins.
He is the one that has firing pins that are so powerful that they drives the case, bullet and powder forward until the shoulder of the case strikes the shoulder of the chamber. I have given up on getting him to consider other alternative options.
And when it comes to verifying one of the 'other' North Texas guns smiths and I grew up within a mile of each other and attended school together for 9 years starting in 1952.
F. Guffey