Serious question: Are anti-material rifles commonly used by cartels?
Yes but for different uses than a normal gun would be used for. The Mexican police and army have been trotting out more of their armored vehicles to try and combat the cartels. .50 Cals and other anti-material rifles function as the counter to those armored vehicles while being a lot cheaper than a smuggled rocket launcher.
You can find lots of videos of them using them, especially on reddit, can’t exactly remember what sub though, Cartel stuff is banned from r/combatfootage