The invention relates to a method and an injector for determining a position of a second part (10) inside a stepped boring (6). This part should assume an exact distance (H) from a first part (2). In order to determine the distance (H) between both parts (2, 10), a collar (3) is firstly introduced into a second boring (6b) of the stepped boring (6) until it rests upon a step (16) of the stepped boring (6). Afterwards, a punch (4), together with a touch probe (5), which is located inside a longitudinal boring (d), is placed upon a lower annular surface (17) of the collar (3) or on an underside (17a) of the first part (2), and the collar (3) is compressed until the predetermined distance (H) is obtained. The distance (H) is measured to a reference measure (x) between a projecting end piece (E) of the touch probe (5) and a reference mark (B) outside of the punch (4). The stamping process is stopped once the reference measure (x) has been obtained.