Google’s latest policy change covering its online shopping center has Second Amendment groups up in arms, and has stirred up the historically tense relationship between Google and the political right.

The search engine giant announced at the end of May that it would change how it lists certain items in search results through Google Shopping. The policy change included a prohibition on listing sites that promote and facilitate weapons sales — a move Google said it made in order to “comply with local laws and regulations.”

Google is undertaking a broader effort to transition its Shopping engine into a commercial site akin to Amazon and eBay, by bringing the service in line with policies it already enforces for its AdWords paid advertising program.

AdWords publishers are not allowed to place Google advertisements on sites that “sell, facilitate or advocate the sales of weapons and weapon accessories.” Google ads are, however, allowed to appear on sites which discuss “the sport of hunting.”

On June 28, the firearms magazine Guns & Ammo notified its online readers about Google’s policy change when it published a letter from Google that notified firearms merchants about the policy change. The letter quickly circulated through gun-owner forums and blogs.

In the letter, Google wrote that its policies are “often more restrictive than the law, because we need to be sure we can offer services that are legal and safe for all users.”

The Daily Caller first reported Friday that some gun owners have considered voting with their feet, and switching their daily online searches to Microsoft’s Bing.com engine. Bing still lists firearms and weapons in its shopping results.

The National Rifle Association Institute for Legislative Action said on its blog Friday that Google’s policy change “appears to be a calculated political statement by Google at a time when most other large online retailers and search services are increasing the level of information they provide and the number of gun-related products they offer for sale.”

Google’s historical alliance with the Democratic Party, with advocacy groups on the political left, and most notably with Barack Obama’s 2008 presidential campaign, caused many conservatives to view the company with suspicion. Google’s close ties to the White House during the initial years of the Obama administration did nothing to ease those concerns.

The company has since balanced its financial support of political campaigns on both sides of the aisle, and built policy coalitions with right-of-center advocacy groups and think tanks.

And when Google hired former Republican Rep. Susan Molinari in February to head its Washington, D.C. lobbying operations, many saw signs that the company had wised up to the ways of bipartisanship. National Journal noted that Molinari came aboard “at a time when the search giant is under intense anti-trust and privacy scrutiny from regulators and lawmakers alike.”

Google’s apparent move in an anti-gun direction, however, is nothing new for firearms retailers.

“For years, Google has refused to sell preferred advertising to sellers of these goods,” said the NRA. “That means Google search results don’t show those products in featured positions, such as at the top of the page or on the right side of the screen.”

Google’s advertising policies have also historically discriminated against firearms retailers that lack “premium publisher” status. A Google Product Forum discussion thread in 2010 listed advertisers discussing Google’s policy covering firearms sites that run ads from the company’s Adsense program.

National Shooting Sports Foundation senior vice president Larry Keane said in a statement responding to Google’s recent policy change that it “should know better than to censor the flow of online information.”

Google’s own stated mission is “to organize the world’s information and make it universally accessible and useful.”

Keane said his organization “is attempting to reach Google to urge the company to reconsider this discriminatory policy that is hostile to the Second Amendment.”

He argued that the “robust sales of firearms and ammunition” constituted “one of the true bright spots” of the U.S. economy, “accounting for a 30.6 percent increase in jobs from 2008 through 2011 and an overall economic impact of nearly $32 billion to the nation.”

Keane also noted that “firearms cannot be purchased online and be transferred directly to the purchaser.” Instead, he said, a gun bought online “must be physically sent from one federal firearms licensee to another, with the latter conducting the mandatory FBI background check on the purchaser (represented in person) and then transferring the firearm only after the purchaser has passed the background check.”

Google’s competitors have repeatedly cataloged the company’s efforts to use its sheer size and influence to dominate markets and squeeze them out. That behavior has landed Google in the cross-hairs of U.S. and European antitrust regulators, due in part to lobbying efforts of some of Google’s better known competitors.

The Texas state attorney general is also currently investigating Google for complaints that it has arbitrarily given its own products and services priority over those of its competitors in search rankings.

During the summer of 2011, the company paid the U.S. Department of Justice $500 million to avoid prosecution on charges that it knowingly sold online advertising to online pharmacies, mostly in Canada, that sold counterfeit medications. Google opposed the Stop Online Piracy Act (SOPA), legislation that caused a global uproar from Internet users but was intended to combat rogue websites that profited from the sale of counterfeit goods online.

Google vehemently opposed SOPA and another related bill on the grounds that it would have forced them to accept responsibility for policing counterfeit and pirated goods.

USA Today also reported in February that Rosetta Stone had caught Google selling “coveted top-of-the-page ad space to more than 1,600 rogue websites peddling fake Rosetta Stone” software.

Google’s track record, despite its best intentions, is far from perfect, and gun owners and retailers are pointing fingers.

“Google’s restrictive policy comes at a time when retailers and other online information resources have increased their content about firearms because of consumer demand,” said Keane. “Fortunately, consumers have other online services to turn to instead of Google for their firearms information.”

Google declined the Daily Caller’s request for comment.

Follow Josh on Twitter