If you're tgrying to co z thin wall tube, you ain't gonna do it sithout
pressure casting methods. The surface tension of the silver will keep it
out of fine passages. The surface tension will keep it out of even passages
1/8" or larger so you have to force it into such passages. This is why
there is sling and centrificugal casting methods and the sprue has to be
long enough to provide the pressure to force the metal into the casting.

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Why isn't there an Ozone Hole at the NORTH Pole?