Rifle usage in L/E is not as common and training is more emphasized on handgun. That being said, majority of L/E are undertrained. I did an MP5 class...
No offense, but I'd say you are wrong. There is literally a thread a week on the Hide where some ding dong has screwed up building his AR10. It isn't...
Way back in the before times, in the way back when..before ANYONE made pistol + light holsters.... we carried the Ancient Insight M3 in a sam browne...
The law has been updated several times, most recently with the Whistleblower Protection Enhancement Act of 2012 (WPEA). They're still not worth spit...