Found this thread while looking for something else and it prompted a couple of thoughts.
At the time of the Twilight War, US Army chemical munitions inventory consisted of:
• Sulfur mustard blister agent in 105mm and 155mm artillery shells and 4.2" mortar projectiles;
• GB (Sarin) non-persistent nerve agent in 105mm, 155mm, and 8" artillery shells and M55 artillery rockets; and
• VX persistent nerve agent in 155mm and 8" artillery shells, M55 artillery rockets, and M23 chemical land mines.
I believe the USAF also maintained aerial spray capability but I have no direct knowledge of those systems or which agents they were capable of dispersing.
A real-world per-site inventory of these as of 1997 is available here (the link I posted above is now defunct):
https://fas.org/nuke/guide/usa/cbw/cw.htm
The blister agent is mostly 1940s-50s production. The nerve agents date to the 1950s-60s.
Due to the mustard's age and its long storage period, a large quantity of the inventory has settled and solidified inside the munitions. This is a problem for the disposal efforts currently ongoing at Pueblo and Blue Grass. In rules terms within the T2k timeframe, I would expect this to reduce the weapons' effectiveness in terms of burst radius and damage dice.
The nerve agent is still viable with no effective loss of lethality.
The artillery shells are stored unfused. I have no info on the mortar shells but I expect they also were stored unfused. The M55s are solid-fueled artillery rockets, stored in their transport/launch tubes with both rocket motors and bursting charges in place. They are electrically-ignited - theoretically, an operator can initiate with a car battery. In a T2k recovery/theft scenario, the M55s are the munitions most likely to be usable by marauders, New America, or other factions in the absence of artillery and the requisite skill set.
- C.