Excerpts from handgunlaw.us page for Car Carry in Oregon:
.Oregon has no State law against carrying a loaded handgun in your car as long as it’s : (a) Not concealed or (b) "Not readily accessible." (If Concealed)
(3) Firearms carried openly in belt holsters are not concealed within the meaning of this section
I OC'd on the tour of the Pendleton Woolen Mills last year with no issues.
State Park Carry is also OK.