Interesting question. Some I've looked at seem to be made of what we used to call 'pot metal'.
I've only got 3 CO2 pistols, a pellet firing Crosman 357-6, Legends PO8 BB, & a Dan Wesson 8". Although not often used - summer plinking only - can't see any being around in 50 years time, unlike my post war Webleys.