The C1 SMG used different magazines to the British Sterling, so British magazines do not fit into these pouches. There were a number of differences between British guns and Canadian examples:
- C1 had a one piece bolt, the UK one had a two piece
- different recoil springs
- Canadian magazines had a basic follower (10 and 30 round capacity), UK ones a roller which was far more reliable.
- trigger groups and shape of the trigger gurards are different
- rear butts are slightly different (the UK one is lighter with more holes in the strut)
- mag releases are different
- front and rear sights are different (C1 SMG used the same front sight as the FN C1 and C2 family of small arms, and the front sight adjusting screw was the same as the arctic trigger guard retaining screw on the C1 and C2.
- different bayonets are used (FNC1 on Canadain guns and the No5 jungle carbine bayonet on the UK ones)
- end caps are different
- on some UK versions the protective surfaces were painted, while the C1 SMG was phosphated