subgauge

adjective3

1. •
   Smaller in bore diameter than the standard gauge specified; most often describing a shotgun with a bore smaller than 12-gauge.

   • Features: A gorgeous subgauge for the clays crowd with a hand-polished, coin-finished receiver with full-cover engraving in an organic floral design and with gold inlays and game birds — 2022
2. •
   Having a dimension or capacity smaller than a standard gauge.

   • Balls for bearings generally have gauge intervals of 1 μm and subgauges of 0.2 μm. — 2000
3. •
   Describes a railway track, narrower in gauge than the standard gauge.