Otto,
The majority or these rifles were converted after WW1( the Great War),There were also purpose made rifles also.Clearly since the cartridge predated the war, matches could have been held (and likely were)then,as well as training.As Axel explained in the other forum, post WW1-preWW2 was the big demand for training.BTW it is unlikely that the rear ring was ground, since it had no markings.