As I recall, the Halon type units were discontinued when the agents were found to be depleting the Ozone layer. Now only for very specialized hazards, and only recycled agent.

I would say one reason for Halon 1301 portables becoming very less prominent outside of US Military contracts was that the agent is more suited for total flooding or local flooding in fixed systems - it is slightly less toxic than Halon 1211 so more suited to flooding whole rooms and has a much shorter range being mostly gaseous in the discharge phase (& whilst not invisible it's not as visible as say a CO2 discharging) Halon 1211 discharges mostly in the liquid phase so has a greater throw and is more visible to users and has a slightly better inhibitory factor giving it an edge in performance which is important with limited agent systems such as portables. Here in the UK we didn't have Halon 1301 portables and jumped straight from CTC & CB to Halon 1211

I have one of these 1301 units still sealed from 1970. General branded Property of US Gov. the bottle if it’s not punctured can separate from the discharge nozzle assembly by loosening a connecting thread to it. There’s a rupture disk at the top of the unit. I think mine came out of a MBT or Helicopter like a UH-1 Iroquois.

Nice Video, long time since you posted.

Looks like CO 2 to me

Squad 51 KMG-365