Exactly how many weighed ounces/drams of sterling silver scrap
would melt to fill a certain volume of an [such as 70 x 40 x 4mm]
Look up the density of Sterling silver; it's 10.5. That means that
1cc of silver weighs 10.5gms.
Next calculate the volume of the mold in cc, which, in your case is 7
x 4 x 0.4 = 11.2cc
Since each cc will weigh 10.5gms, the total weight to fill the mold
will be 11.2 x 10.5 = 117.6gms
Since your mold is measured in metric, it's probably easiest to
weigh the silver in metric, in which case you need 117.6gms of scrap.
If you really want the weight in Imperial units, 117.6gms = 4.148175
oz Since 1oz = 16drams, you need 4.148175 x 16 = 66.3708 drams.
If you want to work directly in drams, then 10.5gms = 5.926drams.
so 11.2cc of silver will weigh 11.2 x 5.926 = 66.3708 drams
Regards, Gary Wooding