[Freedom4US]

Ya, that's my whole point. What do we do when existing
stocks run out? I guarantee any replacement will probably
be heavier, or less effective, or more expensive. More likely all three if had to bet on it.

[TADSLOS]

I seem to recall that there is or was an exception to retaining some types of halon systems based on their unique uses and small quantities. Anyway, you're right. It's an effective and relatively lightweight chemical and would be hard to replace in closed systems like an M-1 or an aircraft engine compartment.