AEP (Automatic Electric Pistol)

The same motor-gearbox-piston chain as an AEG is scaled down to fit a pistol grip, powered by a small rechargeable battery rather than gas. That makes an AEP immune to cold weather and gas leaks, and lets it run indefinitely off a charged battery the way a rifle does.

The trade-offs are weight — the gearbox and battery make an AEP noticeably heavier and more front-heavy than a comparable GBB pistol — and no felt recoil, since there's no reciprocating slide. AEPs are most common as a reliable backup sidearm for players who don't want to carry spare gas.

A common trick to offset the extra weight is fitting a smaller, lighter battery than the frame technically allows, accepting a shorter runtime per charge in exchange for a sidearm that still points and draws quickly.