Quote Originally Posted by tacfoley View Post
My Parker-Hale Whitworth rifle has what Parker-Hale described at the time as a 'Patent or High pressure' breech. The .451cal hexagonally-rifles bore terminated at the breech end into a reduced volume chamber about two inches long, this effectively raising the internal pressure on ignition over that of the larger, full-calibre 'hole'.

tac
That does sound a lot like I imagined the LePage breech as earlier described. Clearly there are more than one breech designs and patents to go with them. Ever the search for improvement.