Thanks to all.
More detailed photos of the 1907 stutzen Mauser bolt.
Sincerely, I think that kuduae hypothesis is the good one. However, if a new bolt has been fitted, the job was done at Mauser factory, with new proofing and with all parts perfectly numbered and finished.
What remains most interesting in this story, it's that they have used an old transition bolt.
Also, for info, the two CIP sheets for the 8x60 and 8x60S.

DORLEAC
www.dorleac-dorleac.com

CIP 8x60

CIP 8x60S