You don't need gauge pins to check throat diameters (although they are nice). Simply drive a soft slug through from the front, any kind of soft lead as long as it's a skinch bigger than the throat, then mic it. Repeat in the rest of the throats. A proper diameter lead bullet should be able to pass through a throat with moderate thumb pressure.
Same rule applies to jacketed but obviously you're at the mercy of the bullet manufacturers, not much you can do about it if they're too small (but sizing down if too large can be done with a Lee push through die).
