Bill Gates. Source: Microsoft.

Iconic Microsoft (NASDAQ:MSFT) co-founder Bill Gates made the news again last week, but this episode had very little to do with the software giant he started.

This time, Gates is putting some of his considerable wealth to work. Bill and Melinda Gates donated $1 million to support stricter controls on gun sales in Washington state.

It's not the first time Gates has supported Initiative 594, which would require background checks for almost all gun sales in the state uses. Today, only licensed dealers have to perform a background check, while gun shows, online gun vendors, and backyard trades are exempted. Last November, the Gateses contributed $50,000 to the same campaign.

Bill Gates has a long history of battling gun violence. In 2012, the Bill and Melinda Gates Foundation cut its ties with a group called the American Legislative Exchange Council. The Gates Foundation had contributed over $375,000 in support of that group's lobbying efforts behind school vouchers and privatized education.

When it became clear that ALEC also lobbied hard for controversial "stand your ground" legislation, among other controversial positions, Gates and many other supporters withdrew their financial support.

And there's more. In 2000, well-known National Rifle Association backer David Kopel lamented Gates facing off against the Microsoft Gun Club -- no joke -- on gun safety measures. That complaint hearkened back to 1997, when Gates contributed $35,000 to Washington state Initiative 676. The NRA helped defeat 676, which was a more far-reaching bill than the one on the table today, but it was already clear which way Bill Gates was leaning on Second Amendment questions.

Source: Everytown for Gun Safety.

Gates brought some deep-pocketed friends
So Bill Gates is investing a lot more money in this particular gun safety bill. What's more, he's not the only billionaire looking for more restrictive applications of the Second Amendment.

Earlier this year, two gun control groups merged into a single entity on a national scale. Everytown for Gun Safety, as this organization is known, combined one grass-roots effort with the big-money firepower of former New York City Mayor Michael Bloomberg.

Bloomberg, who with a net worth of $33 billion ranks among the 20 richest people in the world, put $50 million into Everytown. Superinvestor Warren Buffett, who duels Bill Gates at the very top of the global net worth lists, also supports Everytown, alongside a number of other familiar names .

Yes, Everytown is also lobbying in support of Washington's Initiative 594. This is starting to look like a concerted effort.

Don't expect an easy victory
But even with that financial backing, initiative 594 is far from a slam-dunk win.

Several groups are lining up on the other side of Washington's Maginot Line. Two different law enforcement organizations oppose the background checks. A diametrically opposed measure, Initiative 591, seeks to limit background check even further with the backing of the usual suspects.

Both 591 and 594 appear to have enough support to make it into signed state law today. If that happens, it'll be up to Washington courts to settle the matter.

This armed/unarmed conflict is widely seen as the start of a larger Second Amendment debate across the nation. For example, most U.S. states have enacted weak regulations on child access to firearms -- or have none at all, like Washington. The handful of states with strong requirements for safe firearm storage might soon get some company if the pro-594 billionaires win out in the Pacific Northwest.

So that's where we stand today. Gun control activists are facing off against firearm enthusiasts, with emotions running high on both sides. Ballot boxes and courtrooms will settle the matter, at least for now, and Bill Gates' millions may or may not tip the final scales.

According to an AP report, Initiative 594 has raised about $3.4 million from supporters so far. 591 has collected over $1 million. Both campaigns are expected to see an influx of new donations after the Labor Day holiday.

The SR9 9mm Luger pistol is one of Ruger's most popular self-defense models. Source: Ruger.

What's really at stake here?
Make no mistake -- it's not all about defending or challenging the Second Amendment for ideological reasons. There are big dollars at stake here.

Sturm, Ruger (NYSE:RGR) sold $688 million worth of firearms in 2013, mostly to private American citizens. Meanwhile, Smith & Wesson (NASDAQ:AOBC) shifted $627 million of pistols, revolvers, and rifles. Only 3% of S&W's sales fell outside American borders, and 90% came from domestic consumers.

All told, Smith & Wesson sees a $5.5 billion market for handguns and rifles, and that doesn't even include shotguns or ammunition .

These companies have billions of reasons to fight for the most open interpretation of the Second Amendment possible, which should lead to increased sales in their favorite market. It's a thriving industry with both the financial muscle and the lobbying know-how to put up a serious fight against the likes of Bill Gates and his bottomless pockets.

Whether you're for or against Initiative 594, rival bill 591, or the right to bear arms in general, this Washington state battleground deserves your attention. No matter who wins, this fight has already caught the eye of many business giants and is poised to make a difference to American gun politics for years to come.