A pistol-to-rifle conversion kit (100) includes a rifle body (26) that includes a lower receiver (28), which includes a grip mounting portion (30), which is rearwardly adjacent to a trigger guard (32), which is rearwardly adjacent to a magazine well receiving portion (34). An auxiliary trigger (46) is sliding mounted in the rifle body (26) and includes an elongate member (48) and a forward trigger interface member (50), which extends from a forward portion of the elongate member (48) and which is configured to interface with a trigger (13) of a pistol (14) mounted in the rifle body (26), and a trigger member (56) which extends from the elongate member (48) for directly contacting a shooter's finger.