The Oregon short barrel rule applies to rifles and shotguns, but NOT to handguns. It is illegal to carry a concealed firearm without a permit, but a handgun in a holster is NOT concealed. No minimum limit if you carry it in a holster.
You would have to either look it up online or talk to a person who would know. The information is out there. You could ask a cop about it. You could go to a law libray to find out also. You can find the information almost anywhere on the net.