Gun

In Castlevania's universe, the gun is a projectile-firing weapon in which its ammunition may consist of normal bullets or magical properties.

Sorrow series
In the Sorrow series, 3 guns exist that can be equipped. These are the Handgun, Silver Handgun and the Positron Rifle, which is strangely the only piece of futuristic weapon in the series.

Order of Ecclesia
Albus wields Agartha, a gun which fires both normal and magical bullets. Although he already has a weapon, he can still equip Glyphs(specifically: Ignis, Torpor and most importantly, Acerbatus) and use Agartha to fire them.