the metric capacity you suggest - and regret I can't see anything on the bowl - would probably indicate a Continental origin - Sowerby did some large capacity similar shaped glasses (up to a pint I think), but theirs carry imperial measurements.
If the gadget mark you refer to appears on the under side of the foot then it's a shears mark - gadget marks only ever appear on the top sides of feet. Your suggestion of date is probably about o.k.
The other rummers showing rough scars under the feet, may have been pub or tavern glasses - they possibly date to anywhere from 1870 to 1920, but difficult to be sure from screen pix only.
I think Keith is getting good at these things - perhaps he might look in
