AXSR Barrel threads

Without a makers mark I doubt you could tell who made it. You can get imperial and metric thread gauges to measure a thread pitch. Amazon has cheap ones for $10.

A barrel blank will have the specs punched into the end and/or a sticker. Once I am done reaming and threading the barrel you can’t tell anymore and just have to trust the gunsmith.

Wintac and Proof seem to be the most common for AI barrels. Mile High has some barrels with metric threads if you want to look.

If you have a caliper, measure the outside diameter of the muzzle threads.
5/8=.625
M18=.709

+1 use your measuring stick