"They need to have thorough background checks"  The killer in Orlando had multiple background checks, worked at an armed security guard company and legally purchased both firearms according to the ATF. He had also been interviewed by the FBI three (3) times.

 (Florida imposes a mandatory three-day waiting period, excluding weekends and legal holidays, between the retail purchase and delivery of any handgun.) 

Your 'volunteers' would not be as checked out as he was.  That dog won't hunt.