These terms are confusing, yet common "currency" when discussing pocket watch cases. The "ounce" rating seems disconnected from any actual weight or even dimension. Can anyone explain these seemingly archaic reference terms - so that they make sense?

The ounces are usually for the weight of gold in the case.

I believe these would refer mostly only to silver content cases. That number would refer to total alloy weight in Troy ounces. Any accessories such as stem crown crystal springs etc. are not referenced in the quoted number.

Paul, can you post a picture of a silver watch case with it weight marked?

The ones I see are usually coin and early american

3 would generally be accepted as 3 oz

A silver filled case

Another very early case

2 oz

Sterling 3

Seems to be the 18s are the ones usually marked and even those are limited. When I hear oz's in larger numbers I automatically think silver.
The title mentions 8oz, That sure would be huge, never seen one of those yet.

An 18s dwarfed in 5oz

Paul - thanks for the info, it really helped! Is it fair to say, that oz weights only appear (not always) on the cuvette of silver alloyed cases? I've never seen markings on gold-filled or silveroid-type cases. Are 16s cases ever marked? How rare are 5oz and up cases? I only have one 5oz coin case on my Illinois 18s grade 106.