A customer shops for a pistol at Freddie Bear Sports sporting goods store on December 17, 2012 in Tinley Park, Illinois. Scott Olson | Getty Images News | Getty Images

Even if you haven't actively been seeking gun stocks, you could still be an investor in them. Many companies have ties to weapons, either directly or indirectly. And just owning a general index or mutual fund could give you some exposure — even in a retirement fund like your 401(k). There are some signs to look for to assess whether you are supporting the gun industry through your investments.

Stocks to look for

There are two gun manufacturers that are publicly traded U.S. companies: American Outdoor Brands, parent of gunmaker Smith & Wesson, and Sturm, Ruger & Co. Notably, American Outdoor announced this week that it plans to split into two publicly traded companies. The deal will separate its Smith & Wesson unit from the company's outdoor products and accessories business. The company's stockholders will own both companies and be able to decide on their investments after the separation. One other publicly traded company, Vista Outdoor, sold two firearms brands, Savage Arms and Stevens, in July. The company still manufactures ammunition.

Both American Outdoor and Ruger are small capitalization companies. To be invested in those, you would have to own a fund with exposure to small cap stocks, according to Jon Hale, head of sustainable investing research at Morningstar. Those holdings could come in a variety of forms. You could own a total market index fund, extended market fund or a small cap index fund that includes those two companies, Hale said. "Chances are, if you are an investor who has small cap exposure and it's an index fund, you're going to have exposure to those two companies," Hale said. In contrast, actively managed funds that include small caps are less likely to invest in either company. Out of 500 funds in that category, just 32 included Ruger and 24 had positions in American Outdoor Brands, according to Hale's research. A traditional S&P 500 index fund would focus on larger cap stocks, and therefore is not likely to include those companies.

How funds score

That doesn't necessarily mean that you don't have financial ties to guns or weapons, said Andrew Behar, CEO of As You Sow, a non-profit foundation focused on corporate social responsibility. Behar's company provides a website, Weapon Free Funds, where you can see how specific funds score on weapons exposure. A search for a traditional S&P 500 fund, the SPDR S&P 500 ETF, for example, shows that it is exposed to 17 weapons stocks, including 16 with ties to military contractors and one to civilian firearms. The top holdings with exposure to weapons, in terms of dollars invested, include Berkshire Hathaway Inc., Boeing Co. and Walmart Inc.

Ways to limit exposure