I forgot where I read this but apparently the US border patrol stationed at actual border checkpoints were apparently equipped with .50 bolt action rifles or even M16s chambered in a shortened .50 cal round (either .AE or Beowulf) because apparently a 50 round is the only round that can reliably penetrate an engine block to disable a vehicle from a frontal hit if a car tried to rush through the border barricades.
Any truth to this? Obviously inspired by recent events.