Thanks all for the info. That's a big help. Am I correct in assuming it was made post WW1 (square PG rather than a rounded one)?
The bore has cleaned up nicely and a field test is planned soon with some 140 gr Woodleighs.

This rifle has certainly rekindled my interest in Mauser sporters. I went searching for a suitable reference book & someone suggested "Mauser: Original Oberndorf Sporting Rifles" by J. Speed. Unfortunately it is out of print & 2nd hand copies appear hard to get hold of. Is this really the case?

Spud