The local market should bury the paper by boycotting any advertiser.
E David Quammen articulates an idea I agree with, although I would suggest a nuance to the strategy: If you try to boycott all advertisers, the amount of supporters will be so diffused that most businesses won't be affected--if even aware of it. Face it, we've seen how most gun owners are unwilling to lift a finger and get involved, generally the same ones who bluster about "cold dead hands."
Pick ONE advertiser, a major one like a local car dealer, and first ask them to contact the paper and let it know they don't appreciate its editorial positions dragging them into the middle of a controversy with their customers--that's not why they advertise. For leverage to encourage them to do the right thing, you might want to tell them you are also asking their main competitor to do the same thing. And you never know--the owner might be a gun owner who is just as PO'd as you, so give them a chance to partner with you first by keeping things polite.
I would think a campaign involving a targeted local business getting a hundred or so letters and phone calls might actually produce some results. And if the business is unwilling to contact the paper and threaten to pull its advertising, then would be the time to escalate to the boycott stage.
What this needs to work is for one local gun rights activist to become the leader and coordinator. Start a blog. Hold a meeting with local gun owners. Recruit support from local gun shops, ranges, clubs--and if any advertise in the paper, perhaps they should become the first business approached, especially if they don't wish to involve themselves. As for membership, it would seem the paper has provided us with a great starter list...