Having left the army that year, Aasnæs became the World Champion in the individual 100 metre running deer double shot event in 1947. He was also part of the Norwegian team that won a silver medal in the running deer double shot event, and bronze medal in the running deer single shot event. At the 1949 World Championships, he won a gold medal with the Norwegian team in the running deer combined event. In 1952, he won two team gold medals at the World Championships, in the running deer single shot and double shot events. At the 1954 World Championships he won a bronze medal in Olympic trap.