Any idea what these are? 303 barrel gauges?

[Surpmil]

The brass or copper "caps" on these appear to be smaller than the gauge diameter so perhaps they were just a convenient way to mark the gauge clearly and easily with the maker's name, size etc. rather than trying to acid etch, or engrave/stamp the gauge before it was hardened and ground.

If the 125, 150, 175, 301, 302, 303 etc. refers to the diameter, as it seems to, either I don't know enough about gauge markings or there is something else going on as the 125 gauge appears about the same size as the 303 gauge.

Price certainly seem to have gone up since we started talking about them!