The last use of centerfire rifles at 300 meters in the biathlon (and free rifle three position matches) was back in 1976. That's when the IOC decided that it was too costly and improbable for many countries to build ranges with a big enough safety zone behind them for both free rifles shot in 3 positions and biathlon rifles to be used. So they went to 50 metres and rimfire 22's for all rifle firearms shooting in both disciplines so more countries could more easily get into it.
Eley makes biathlon rimfire ammo especially formulated with primer and powder to work well in very cold weather. I think Lapua and RWS also make it.
Eley makes biathlon rimfire ammo especially formulated with primer and powder to work well in very cold weather. I think Lapua and RWS also make it.