Rusty:
I appreciate the fine credentials of your friend, but with respect, I have never known the actual pressure of a single cartridge I ever fired in my entire life, and that is quite a few hundred thousand counting shotshells and target pistol loads. Several thousand of them were in British double rifles, all handloaded by me.

I know the pressures have always been safe, since I've never damaged a gun.

With reloads I control the quantity and burning-rate of the powder, and can measure the velocity from time to time. This I compare with recommended loads proven safe by comparison with the charges for which the guns were originally proved. Wright's book is a good source of pressure data, undoubtedly the best published reference to date.

Can anyone here tell me the actual pressure of the last cartridge they fired in a double gun? Of course not!

Perhaps it is irrelevant after all.................

And as for the problems understanding Graeme Wright's book, blimey! Couldn't be much simpler. A lot of 'mole-hill mountaineers' might see the need to criticise that marvellous reference, but I don't see anything even remotely near it coming from the quill of any of its detractors.