Round pistol grips on bolt actions were quite common before WW1. All commercial Mausers up to 1912 had such stocks, see Jon Speed’s books. Here are (again) some more examples:
Haenel 1900

G.L.Rasch, Brunswick, M93 Mauser action

DWM Plesier Mauser M93 action, 7x57

1908 W.Foerster, Berlin, in 9.3x62

Schmidt & Habermann M21 in 6.5x54 Mauser K

Haenel M 1909

V.C.Schilling M88 action

G.Gibbs, Bristol, Mannlicher M95