I'd bet 90% of gun owners would support virtually anything after being subjected to four months of corporate gun industry propaganda. You know, bullshit like how owning a gun "empowers" you.
How much money does the NRA have? How big is the gun industry? How much money does the mainstream media and the federal government have? Or OFA and Soros, for that matter?
Worth a bit of Googling. Methinks you don't have a good order-of-magnitude estimate of how much money is on each side.
The gun industry is $32 billion. Mainstream media and fed government are not on a "side". Soros is $20 billion but a tiny fraction of that is devoted to advocacy. OFA, assuming you mean Obama For America (?), is not a single issue entity. The gun corporations are, and that single issue is maximizing profit.
Do you think the gun lobby helped to write the second amendment?
I'd also like to point out that the gun industry doesn't really run ads in the same way most industries do. I've never seen a single gun ad outside of a gun magazine.
