[2] Marion was part of the winning Canadian teams in the 1972 and 1982 World Long Range Championships.

[2] Along with William "Wilf" Baldwin, he won the gold medal in the fullbore pairs event at the 1986 Games, held in Edinburgh,[3] with a score of 583 out of 600.

[4] For the 1998 games, in Kuala Lumpur, technical difficulties forced him to use his second choice of rifle:[2] he and Jim Paton placed second with a score of 298 out of 300.

[6] He won the Dominion of Canada Rifle Association's fullbore championships twelve times, a record as of 2023[update].

[7] Marion was capped forty-two times in the Canadian team for the Imperial Meeting at Bisley in the United Kingdom, more than any other shooter.