Darn--I knew I shouldn't have posted that quote, because it's confusing.
Treblig, what they're doing is saying that the shells are OK both in guns marked 3 tons (standard 12ga Brit marking, through the late 80's) or 850 bars (standard marking from the late 80's until, I think, quite recently). But you don't arrive at a psi reading by multiplying the British "tons" designation x 2,000. And an 850 bar gun, according to the Birmingham proof house, has an equivalent service pressure of about 10,700 psi. (You can't get there either by "doing the math", because the Brit markings are lead crusher bars rather than electronic transducer bars. It's like the old LUP measurements in reloading manuals vs psi.)
I don't know whether King has inquired about that particular load, but it's certainly under 10,700 psi, and I'd guess more likely somewhere in the 8,000 psi range. One source I have puts the maximum service pressure for a 3 ton gun at 9,000 psi. I think that may be on the conservative side, but then when we're talking pressure, the conservative side is a good place to be.
