atkinson6 - as I recall, when the Maharaja of Surjoja's much used Rigby 416 double came onto the market in the UK, the photos didn't indicate that it had been tightened - and could not have been loose since that sort of thing is a no-no there! In my view, that is probably a testament to the Rigby action strength (not sure whether it was rising bolt, or a later Webley & Scott) or quality of the original action fitting by Rigby's! Quite probably both! The point is, on a properly made gun, 416 pressures are probably OK, dare I say - unlike another well known London maker's (did someone say "Legends in their Minds"?) heavy doubles, or quite possibly anybody else's, with the exception of a well fitted Webley & Scott PHV1 action. The real issue is case extraction - nobody's figured how to make it work on a rimless case!