A Historical Cannon Range?

The Lost Coast Outpost reports an inert artillery projectile was found over on Pine Hill. No worries, and it was taken off and destroyed by the bomb folks for practice. I was intrigued when I first read of the find, though. 

You'll recall Fort Humboldt is close by where the munition was found. Back when I dabbled in treasure hunting I got to thinking about Fort Humboldt and whether that garrison had a cannon. If so, they must have had a range of some sort where they could fire it for practice. If the impact area was to the south, east or north of the fort, there might still be some old cannon projectiles laying around out there.

Brought that up with an expert treasure hunting friend of mine. He thought it a good tip, but never did any further research on it. Neither did I.