Shares of U.S. gunmakers popped higher at Thursday's market opening following a Florida school shooting that left 17 people dead on Wednesday. Gunmaker stocks often see quick increases after mass shootings, as enthusiasts apparently buy more weapons because they fear mass killings could result in new government restrictions on gun sales.

Pure gun plays Sturm, Ruger & Co. (RGR - Get Report)  traded as much as 2.8% higher in early trading Thursday, while American Outdoor Brands Corp. (AOBC - Get Report)   rose as much as 4.5%. However, both later pulled back to near the flat line.

Sturm closed trading down 0.2% while American Outdoor closed the day up 1.5%. 

Gunmaker stocks often pop following mass shootings, as enthusiasts fear tighter gun laws could result.
Gunmaker stocks often pop following mass shootings, as enthusiasts fear tighter gun laws could result.

Olin Corp. (OLN - Get Report) , a company that sells a mix of gun brands and other products, also rose as much as 2.7% higher and closed the day up 1.56%. So did fellow mixed-product gunmaker Vista Outdoor Inc.  (VSTO - Get Report)  , which tacked on 0.3% early on but closed the day down 0.36%. 

Nikolas Cruz, 19, was taken into custody Wednesday in the neighborhood surrounding the school after his alleged shooting spree in Parkland, Fla. He was a former student who was expelled from Marjory Stoneman Douglas High School for unspecified disciplinary reasons.