Jack: could you please post an ultra close up of the barrel flats of your BNP GHE and thanks!
Bruce: in 2002 Tom Armbrust tested and the 16ga reloading group reported two batches of the old 16g Federal Game Load 1 oz 1165 fps at 9160 and 9633 psi. All I could get Federal to tell me on inquiry was "about 10,000" in order to assure funtion in autoloaders. It's called Game-Shok Game Load now
http://www.federalpremium.com/products/shotshell.aspx
LTC Calvin Goddard writing in
Army Ordnance in 1934, stated that Hunter Arms proof tested 12ga 2 3/4" chamber barrels at 14,300 psi.