The Military under reports a lot. They have homicides and drugs on base but you hardly hear about it outside of an Active Shooter situation. So nothing new there. However From my own military experience (and the USAF carried Berettas with a round in the chamber and on fire in DA mode) there’s just not an abundance of ADs. Yea ADs happen and usually at clearing barrels. Just not in epic numbers.
As far as 140,000 Sigs and an Agency. DHS encompasses Customs, USBP, Secret Service and a few others which adds up to almost 100,000 Glock 47 so you can have a few hundred thousand SIG 320 carrying LE agencies if you combine just a few. Some of the Sig Departments. State agencies alone TX, OK, WY, OH, VA, NC and others that standard issue then there are the scores of Privately Owned Weapons that are approved for duty. Like the Glock 40 S&W KB the SIG 320 AD is over reported and sensationalized in LE agencies.
Also factor in Out of the State Police agencies mentioned your up to about 15,000 troopers or more that Use their Handguns more than the Military (how many Military members carry loaded handguns on a day in day out basis in a non training capacity?) With MPs and a few others the numbers are not going to be that high they aren’t carrying the hundreds of thousands of guns at once. And how many Military Units do chamber live ammo as a condition of approved duty carry? I know the USAF does but I can’t speak of the other branches.