| 摘要 |
<p>One-piece plastic injection moulding of diabolo shape is inserted between the powder and shot in a cartridge. It has two relatively thick skirts each joined by a thin flexible ring to a thicker central base to form an external groove between the two cups. Pref. the spacer is symmetrical and reversible. The thin rings may be tapered so that the groove is a vee, or may be flat so that the groove is a narrow slit.</p> |
