When the "new" barrels were made, the 6.5x52R aka .25-35 Win was regarded as an ideal roe deer, fox and other varmints + small game cartridge. It's use on larger game like boar,red, fallow deer was illegal since 1934, as it did not meet the then minimum criteria: Either 200 meterkilogramm energy at 100m or 10 gramm bullet weight(to keep the prooven 6.5x54 M-Sch legal), though it met the 6.5mm diameter minimum for larger species than roe deer.
Today German legal Minimum specifications:
Roe deer: energy 1000 Joule at 100m (so the .222 Rem is the smallest legal roe deer cartridge)
All other hoofed game: bullet min. 6.5mm and energy 2000 Joule at 100m.