| 摘要 |
<p>The marker projectile is a thin envelope of expanded polystyrene, made in two separate parts and contg. a pigment powder. To enable such an object to withstand a firing charge sufficient to project it with fair accuracy, it is put in a light metal cup, which is fired with it, but held back captive on a cord fastened to the base of the cartridge. The projectile sits on a block of plastic inside the metal cup, and is held in it by a waxed card but across the mouth. The exterior of the metal cup fits the inside of the cartridge closely, and the cartridge is made long enough to guide the trajectory of the cup (and also the marker projectile it contains) when the cartridge is fired.</p> |
