Abstract: Two symmetrical, axially separable barrel halves of plastic material are provided at their confronting end faces with peripheral edge beads each forming a set of axially projecting teeth alternating with gaps of like width, the teeth of each half fitting into the gaps of the other. The free ends of the teeth are provided with radially extending bosses forming two annular crenelations separated by a substantially flat ring zone upon the interfitting of the teeth, this zone receiving a broad strap inserted between the two crenelations to hold the barrel halves together. The peripheral edge beads are further provided, radially inwardly of the teeth and gaps, with axially extending tenons and mortises or equivalent tongue-and-groove formations to provide a supplemental bracing effect. The inner strap surface may be correspondingly beveled to exert upon the free tooth ends an elastic biasing force urging the two barrel halves toward each other in the axial direction.