I've not seen a Wundhammer with the swell. However Harvey Rodgers incorporated the feature on many of his stocks. It is just a narrow ridge running along the side of the grip. Hardly noticeable until you grip the stock. It lays just perfectly in the crease of your palm.
![[Linked Image from i.imgur.com]](https://i.imgur.com/0uDaUjY.jpeg)
![[Linked Image from i.imgur.com]](https://i.imgur.com/wTkoE17.jpeg)
![[Linked Image from i.imgur.com]](https://i.imgur.com/PuJz49l.jpeg)
Bottom photo the second rifle from the top, and the bottom rifle has the swell, others do not. Kind of off topic, but for those seeking a Rodgers rifle, watch for vintage smallbore target rifles. His boss at Hart Arms, Arthur Hart, was an avid smallbore shooter, and as such catered to the target shooting community. Lots of Winchester 52's out there wearing Rodgers stocks.
The swell does add to the difficulty when checkering the stock.
John