>>542443145
>>542443220
You fire actual bullets and slugs. The aetherotransformer and power the gun and gadgets with the user's converted aether, but you're still shooting a gun.

EE1
>Aetherotransformer: This device converts the wearer's aether into lightning-aspected energy, which is in turn stored within the transformer's crystal cores. The machinist then draws upon this accumulated energy to both power and enhance her unique repetoire of weapons, requiring her to master skills far beyond those trained by any mundane musketeer.

>Slug Shot: Swapping out standard bullets for an oversized slug, this shot impacts the target with shuddering force. In this fashion, a trained machinist employs various techniques to take advantage of a multitude of custom ammunition.

EE2:
>Like the bard, the gun-wielding machinist keeps her enemies at a safe distance, and thus prefers lightweight and mobile defensive gear. In fact, she may even find the same garments worn by archers on the battlefield serviceable for her purposes. Still, the comparatively high-maintenance nature of machinist weapons has led to demand for specialized attire, which allows them to keep spare parts, maintenance tools, and the aetherotransformers that power their firearms and turrets close at hand.

I don't think it gets any clearer than "aetherotransformers that power their firearms", but this myth never dies, so go figure. And it's not just the lorebook either, the job quests make it clear. For example:
>Stephanivien: By redirecting the energy generated by your aetherotransformer, you will be able to charge a bullet with lightning, and thereby stun the target of your shot.