Trying to help the owner of a "conical flash-hider" .
Hope to get photos soon, but it is described as 200mm long and with clearance for a "serious bullet"
Apparently there is also a "mandrel" to help tidying up dents in the cone.
My wild guess is .50 Vickers, as used in quad-mounts on Royal Navy vessels. Also used, apparently, by the LRDG in North Africa. but not with the heavy quad deck mount,
