DT: I was a bit apprehensive about posting this data and we talked it over quite a bit on 16ga.com. The back of my Eley Grand Prix loads say the same thing and Eley never responded to 2 requests for pressure data (please see this thread
http://www.16ga.com/forum/viewtopic.php?t=2410 )
Larry understands this better than I do and had an article in Shooting Sportsman a couple of years ago about proof testing. Federal responded to my request for pressure infro regarding their 16g Game Shok 1 oz at 1165 fps and said only 'it runs between 9000 and 10,500 psi.' That has been the standard 16g 'Field' load for more than 80 yrs and I must assume it is acceptable in '3 ton' proved guns. You'll note though, from the above thread, that several makers have 1 oz loads running closer to 8000 psi.
You'll also note that the shot size data from Eley is different that TWO other websites. England and American-2 nations separated by a common language!
BTW: this pressure-speed chart from B&P helps understand the relationship between psi/bar
http://www.bandpusa.com/files/db_trio.pdf 
