Caliber is a critical aspect of ammunition, but it is something that is also often misunderstood or misrepresented. As it relates to firearms, caliber by definition—according to Merriam-Webster—is either A: the diameter of a bullet or other projectile, or B: the diameter of the bore of a gun usually expressed in hundredths or thousandths of an inch and typically written as a decimal, such as .35 caliber.
Federal Premium Ammunition is producing Train + Protect loads using 85-grain .380 ACP ammo, 125-grain .357 Mag. ammo and 158-grain .38 Spl. rounds.
A good variety of 9mm semi-automatic pistols will feed nearly any 9mm ammo without issue. When it comes to 9mm revolvers, though, owners must be careful with ammo selection.