Socially responsible investing, or SRI, has long been known for avoiding ownership of shares of gun makers and other weapons manufacturers. However, in the wake of several particularly tragic and massive shootings recently, investors should be thinking about pulling guns out of their portfolios, regardless of whether they consider themselves SRI investors or not.

Target: Divestment
Some huge investors are already taking this step in the wake of heartbreaking tragedies like the Sandy Hook elementary school massacre.

One of the biggest pension funds in the country, the California State Teachers' Retirement System, commonly known as CalSTRs, is beginning the process of divesting itself of all gun manufacturers as we speak. According to The New York Times, teachers voted in a public meeting against their retirement money being invested in firearms makers.

Because of CalSTRS' responsibility to preserve the money of the educators whose pensions it manages, it may take years to completely divest itself of gun companies' stocks (it took years for it to completely ditch tobacco stocks, for example). However, an institutional investor as big and influential as CalSTRS sends a major message about companies that manufacture firearms.

Private equity firm Cerberus also announced that it's selling its stake in Freedom Group, which makes guns under brands like Remington and also manufactures the Bushmaster rifle that was used in the particularly heinous Sandy Hook shootings in Newtown, Conn.

Dangerous holdings
Along those lines, many people who haven't actively invested in gun manufacturers like Smith & Wesson (SWBI 0.71%) and Sturm, Ruger (RGR 1.37%) may not be completely disconnected from these stocks. These stocks could be in many funds unbeknownst to Americans who are simply trying to save for retirement. For example, CalSTRS owned both through an index fund.

As it turns out, fund giant Vanguard is one of the largest holders of both Smith & Wesson and Sturm, Ruger. Since both companies, as well as ammunition manufacturer Olin (OLN 0.79%) are part of the Russell 2000 and 3000 indexes, they're fair game for index fund holdings.

Domini Social Investments' Adam Kanzer recently examined this aspect of the issue at length, calling on the need for institutional investors to address issues like social harm. Trillions of dollars of mutual fund assets are being allocated into public companies' shares, often with little or no concern for some businesses' long-term negative ramifications on society.

Even some retail companies can be involved in the tangle of controversy. Wal-Mart (WMT 0.46%) pulled down its website listing for the Bushmaster rifle after the Sandy Hook tragedy, although the rifle was still sold in its stores, and Dick's Sporting Goods (DKS -0.07%) actually suspended sales of such guns "out of respect for victims and their families."

Incidentally, earlier this week Wal-Mart did accept an invitation to the White House to talk about the issue with Vice President Joe Biden after having originally declined. Wal-Mart's size and breadth makes it a no-brainer go-to retailer in terms of gun sales. Interestingly enough, Wal-Mart had reduced its gun offerings in 2006, but added such merchandise back into the mix at some of its stores in 2011 due to its struggles to increase its U.S. sales at the time.

Too high a price
I would rather not get into the political arguments about gun control; I believe those are red herrings that miss the real point related to many tragic and violent events. As atrocious as some of the recent incidents of massive gun-related violence have been, I'm in the increasingly vocal camp that believes our society's inability to realistically or constructively deal with mental health issues is the problem more than the instruments through which severely mentally ill people do harm.

Still, I am a proponent of choice, and choosing to try to do what I believe is the right thing. I wouldn't choose to purchase shares of Smith & Wesson, Sturm, Ruger, or Olin for my portfolio. As a socially responsible investor, I am not looking to profit from products that can and do facilitate peoples' violent acts against one another or even themselves.

Not only do I believe this the ethical choice, I also believe it's common sense. Companies that provide harmful products run the major risks of lawsuits, regulatory action, and public backlash, all of which make their stocks risky investments even in the purely financial sense.

Regardless of all the argument and debates, it's time for all kinds of investors to think twice about whether harmful stocks like these are really worthwhile holdings for their investment portfolios. For those of us who know companies are more than just ticker symbols and share prices, long-term investment dollars do send a message of support for companies' business models. Given recent events and their impacts on society, such stocks represent too high a price to pay, so the message should be, "No, thanks."

Check back at Fool.com for more of Alyce Lomax's columns on environmental, social, and governance issues.

Editor's note: A previous version of this article stated that Adam Kanzer works for Reuters. The Fool regrets the error.