Start with the PD and if they say go to the Sheriff then go to the Sheriff. Does your work have any policies with regards to firearms?
That's one of the issues I have... I commute to the bay area, I am in rural areas during my commute with high end computer gear almost daily and I work strange hours. BUT... My employer has a strict no firearms policy, so I cannot use this as justification since they will certainly be contacting my employer if I bring this up.
Crafting your just cause is the second most important thing behind having a clean record.