Why have a safety on even a gas-powered BB pistol? they aren't the kind of thing that'll inflict a wound, except to pride. Unless one of those little plastic balls hits somebody directly in the eye.
IMO in the case of a zombie apocalypse, I'd rely not only on firearms, those I'd save for when they HAVE to be used. I'd be making sure to pack a couple of claw hammers, my sword, an arsenal of chemicals of both the highly flammable variety and the much less friendly kind, along with my gas mask, face shield, goggles etc. thick leather jacket with hastily bolted on metal plates to protect against bites, along with razor-sharp spikes located in strategic areas, such as knees, round my combat-boots on the toes, edges, heels and top of the toes, elbows, forearms, gloves with some sharpened steel nails, the short kind with the wide, flat heads to give a good anchor point, brazed onto metal plates and attached to some thick (and comfy) leather gloves, and the thinner of my spiked collars round my neck, to avoid any brain-hungry undead getting a hold on my neck, whilst the thicker, heavier one goes round my head, with the double row of rusty steel spines, goes round my head, at about forehead height, for a fairly obvious reason, that really isn't going to be very decorative, at least not after an encounter or two with a zombie. That, and I'd be raiding the nearest gun&other weapon store, stocking up, preferably with the owner cooperating as a partner for added mutual survival advantage, but I'd be fully prepared to deploy chemical weaponry in order to eliminate the living and dead-ish alike occupying the premises, after first conscripting the occupants of all pharmacies along the way, for both medical supplies and supplies that could be loaded into syringes and used as paralytics, poisons or both. The contents of my lab of course would be coming along for the ride, and everything from thermite, to sodium metal slugs to be fired from DIY black powder-fuelled weapons constructed from as many metal pipes as can be found, hastily improvized mustard 'gas'es, fire-extinguishers converted into instruments for the propulsion of mixtures composed of something like petro/diesel mixed with motor oil and a mixture of acetone and polystyrene foam dissolved in it so as to make sure it sticks to the target, and an oxidizer in a separate tank, something bloody strong, like chromyl chloride (which is corrosive as hell, starts organics on fire on contact generally speaking along with releasing hydrochloric acid gas and poisonous hexavalent chromium refuse, along with fuming acid when it gets wet) to autoignite the fuel in another modified fire extinguisher, the two strapped together.)
Plus of course, more black powder for the purpose of, A-blowing shit up, and B-a selection of nail-packed, phosphorus-filled and thermite grenades to be launched from something fuelled by said black powder. I think I could find plenty use for the sulfur, the potassium permanganate, the nitrates that didn't go towards things to fire hastily-made bullets and grenades/rockets/mortar shells, and sulfuric acid, along with the glycerine for..well..what glycerine is famous for when nitrated, along with the ethylene glycol, and anything else thats nitratable, and the pounds of magnesium, aluminium, zinc, iron, even the nickel and the copper metal dusts. And a lot of glass bottles, lighters, matches, rags,concentrated sulfuric acid, chlorate salts or if none available, the potassium permanganate and a plastic hose to siphon spare fuel out of cars for when the original lot for filling the first lot of bottles is used up, and as many zombies as possible put back underground. Or at least cremated and left there:P
And then? I'd be going on my own apocalypse. Alive, and intent on A-staying that way and B-making one fucking great big mess and not in the least bit fussy about what I do to make those things happen, raising my own, living horde as I go along, whilst making anything unliving...well....much more un-living. In a way that the term 'trigger-happy' does no justice to so much as merely hinting towards.