Shares of Smith & Wesson Brands Inc. /zigman2/quotes/202273249/composite SWBI -1.05% plummeted 29.9% in afternoon trading Friday, putting them on track for their biggest one-day selloff since March 2020. The gun maker reported after Thursday's closing bell fiscal second-quarter profit and revenue that missed expectations, demand levels declined from pandemic-related highs, and the stock ended Thursday's after-hours session with a decline of about 15%. The stock fell even further after Friday's open, after the parents who bought the gun used by their son to kill four students at Michigan school were charged with involuntary manslaughter. The stock, which was on track for the lowest close since March 5, has now plunged 54.7% since closing at a record $35.40 on July 1. Shares of fellow firearms maker Strum Ruger & Co. /zigman2/quotes/200036418/composite RGR +0.27% tumbled 11.1% toward the lowest close since Jan. 29, and have now lost 29.3% since closing at a record $89.98 on June 30. Year to date, Smith & Wesson shares have lost 9.6% and Sturm Ruger's stock has slipped 2.3%, while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.88% has gained 20.1%.