What is the value of a Hercules gas munitions 38 special pen gun model 30 E4229?

IF your gas gun is capable of chambering and firing a round of live ball ammunition (some of the older ones were) then it requires licensing as a Class III firearm with the BATFE. Possession of an unregistered Class III is punished by 10 yrs in prison, and a fine of $250,000. If not already registered, it cannot be.

If it CANNOT fire ball ammunition, then value is in the $50-$100 range. I do not believe that .38 Special tear gas ammo is still in production. Sorry-