i have been following this thread with interst. The last poster gives it in tonns per sq inch. An engineer i know was asked why he was using such a large hammer so gently instead of a smaller one. The answer was you can give a little hit with a big hammer but not a big hit with a small hammer.
The thread 12bore from hell has me thinking what will a 730gn projectile figures be at 1800fps to 2500fps be. I think some well known calibres may retreat to small rifle status.