Barack Obama, the US president, has called for more research into violent video games in the wake of recent mass shootings. It is part of a range of new measures aimed at curbing gun violence in the US. The gaming industry is quick to point out there is no conclusive evidence linking video games and violence. Researchers have yet to prove a link between gaming and real world violence, but Al Jazeera finds there are strong ties between the industry and guns. Al Jazeera's Kristen Saloomey reports from Springfield in Illinois.