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.
Webley Mk3 x2, Falcon & Junior rifles, HW35x2, AirSporter x2, Gold Star, Meteors x2, Diana 25. SMK B19, Webley Senior, Premier, Hurricane x 2, Tempest, Dan Wesson 8", Crosman 3576, Legends PO8.