Murderous Ghouls Attempted To Hide Their Actions

You can bet the farm this happens all the goddamn time. Only reason to recover the bullets was to hide the caliber that was used.

US special forces 'tried to cover-up' botched Khataba raid in Afghanistan

"US special forces soldiers dug bullets out of their victims’ bodies in the bloody aftermath of a botched night raid, then washed the wounds with alcohol before lying to their superiors about what happened, Afghan investigators have told The Times.
Two pregnant women, a teenage girl, a police officer and his brother were shot on February 12 when US and Afghan special forces stormed their home in Khataba village, outside Gardez in eastern Afghanistan. The precise composition of the force has never been made public."