A pistol frame can include a trigger mechanism recess, an upper rim extending about the trigger mechanism recess, a rear insert recess within the trigger mechanism recess, a left rear rail insert, and a right rear rail insert. The left rear rail insert can include an upper portion including a left rail and a lower portion including a first pin aperture. The right rear rail insert can include an upper portion including a right rail and a lower portion including a second pin aperture. The pistol frame can include a first and second pin hole aligned with the trigger mechanism recess and a pin that can extend through the first and second pin holes and through the first and second pin apertures.