Cue the David and Goliath jokes.
In Tiajuana, Mexico, there is a shakedown and purge of the police department underway due to allegations of corruption. As a result, the police have been disarmed so that their weapons can be used in ballistics tests to see if any were used in a number of murders linked to drug cartels and re-issued slingshots and ball bearings as weapons. They're crude, and definitely underpowered when compared to a pistol, but anything small and hard moving very fast is going to put a hurt on you if and when it hits.