John,
That style of engraving is known as "Rosace", and is usually applied to guns of higher grade than V19-I cataloged that style on V21 grade Darnes.
Does the serial number of your Darne begin with SPC or SPL, perchance?
It was also available in R15 grade guns, at the time. Sometimes you can find a signature of the engraver on the action.
Was the stock extension (nicely done, by the way) done to fit you, or someone else?
Good looking gun. Sorry to hear that you find it unpleasant to shoot. Maybe 28 gauge tube inserts would tame the recoil a bit.
Best,
Ted
