In this episode Bruce and Birdman discuss "What's that number mean?" and firearm terms/definitions; caliber, bore size, metric dimension, gauge size, reloading, and hand loading.
Full Video @ https://youtu.be/095Y_D7n_5g
The Point of Ammo
Caliber is the approximate diameter of the bbl
45 cal .451/1000 of an inch
38 cal / .357
9mm developed in Europe, metric .355 diameter
44 mag .429 dia
Gauge vs. Bore
Gauge is determined by weight in fractions of a pound of a solid sphere of lead with a dia equal to the inside dia off the bbl
1/12 # ball fits in a 12 gauge bbl so 12 gauge
Except 410 which is a bore size of .410 inches but it would have been a 67 gauge although was at one time called a 36 gauge
Safety, safety, and more when reloading