Well if CO2 is now on the radar, the Drulov DU10/Zastava GP 45 is as accurate as an accurate thing, awesome trigger, true blowback semi auto 5 shot and deffo should be in that list.
BTW, I wouldn't store my expensive toys outside in the cold and damp, If security was a real worry a floor safe or pistol/ammo safe in an under the stairs cupboard would keep them cushdy.