Yes. Here is what Brownells says about the Stag Arms upper:
"Purpose-designed upper receiver components are mirror images of the mil-spec right-handed parts, so rounds eject from the left side of the weapon. Now you can build a gun adapted to you, and not have to adapt yourself to the gun. Forged aluminum Left-Handed Upper Receiver comes with the forward assist on the left for comfortable operation by naturally left-handed shooters. Installed ejection port dust cover flips upwards to clear the bolt release on the lower receiver. 13-slot Picatinny rail provides a full 5" for tactical accessories, while the etched position numbers in rail slots ensure repeatability of optic mounting position. Requires the Stag Arms left-handed bolt/carrier assembly and barrel extension, sold separately."