I'm not 100% sure, but I think Tucson does not allow the M4. I'll ask one of the BP guys tomorrow.
IMO, it should be standard issue, just like the Barrette.
Speaking of which, I'll miss mine. We are going to the Glock 9mm that Customs Inspectors carry.
Marine Inspector
I've seen the Naco agents carry the M4 on occasion, especially around the San Pedro.
Gotta run -- renewal class for my CCW.