Pistols with frame inserts have a frame having a grip, the frame having spaced apart upper sidewall portions having upper edges defining a slide interface plane, the upper sidewall portions being planar elements each having inner faces facing each other and exterior faces facing away from each other, each upper sidewall portion defining a side opening adjacent to the slide interface plane and having a perimeter spaced apart from the slide interface plane, a frame insert including pistol action components connected to the frame, and the frame insert having opposed insert sidewalls, each frame insert sidewall having a selected portion registered with and occupying a respective one of the side openings of the frame. The frame may define a cavity width between selected portions of the inner faces adjacent to the frame side openings, and wherein the frame insert has a width at the selected portion greater than the cavity width.