G'Day Fella's,

Maral, I did remember and the muzzle diameter of my .404 is as follows;
At the muzzle of the 24"/610mm barrel, the diameter is, 0.725" or 18.40mm.
It may be a Number 5 or 6 profile?

Hope that helps

Nice looking rifles 458Win, thank you for sharing the images!

Regards
Homer