Thanks Peter, I still don't see why the larger recess is on the left though, when most shooters are right handed. However, if they didn't bother to change the spec from P14 to No4 I don't suppose they'd worry about that either.
It is rather strange to see the detailed drawing posted elsewhere on this site which specifies all the exact curvatures for the front recesses when they apparently have no particular purpose or reason for their configuration; and certainly no logic that I can make out.