Muzzle device for a projectile-firing device

Muzzle device for a projectile-firing device, comprising:-a body adapted to be fixed at a muzzle of a projectile firing device and comprising an axial passageway for permitting the passage of a projectile leaving said muzzle along an axis in a forwards direction and at least one lateral port having an inner end opening into said passageway and an outer end opening at an outer surface of said body, said lateral port having a proximal wall and a distal wall, said proximal wall being situated closer to said muzzle than said distal wall, wherein said distal wall comprises, considered in a plane containing said axis and a midline of said lateral port:-a first distal wall portion having a concave cross-section;-a second distal wall portion adjacent to said first distal wall portion and having a convex cross-section;-a third distal wall portion adjacent to said second distal wall portion and having a concave cross-section; and-a fourth distal wall portion adjacent to said third distal wall portion and having a convex cross-section, said fourth distal wall portion terminating at said outer surface of said body at an acute angle thereto.