Remove the barrell and look at all the stamps on the underside of the block. You will find the date code. Here are the date codes since WW2.
I - 1945; II - 1946; III - 1947; IV - 1948; V - 1949; VI - 1950; VII - 1951; VIII - 1952; IX - 1953; X - 1954; XI - 1955; XII - 1956; XIII - 1957; XIV - 1958; XV - 1959; XVI - 1960; XVII - 1961; XVIII - 1962; XIX - 1963; XX - 1964; XXI - 1965; XXII - 1966; XXIII - 1967; XXIV - 1968; XXV - 1969; XXVI - 1970; XXVII - 1971; XXIII - 1972; XXIX - 1973; XXX - 1974; AA - 1975; AB - 1976; AC - 1977; AD - 1978; AE - 1979; AF - 1980; AH - 1981; AI - 1982; AL - 1983; AM - 1984; AN - 1985; AO - 1986; AS - 1987; AT - 1988; AU - 1989; AZ - 1990; BA - 1991; BB - 1992; BC - 1993; BD - 1994; BF - 1995; BH - 1996; BI - 1997; BL - 1998; BM - 1999; BN - 2000; BP - 2001; BS - 2002; BT - 2003; BU - 2004; BZ - 2005; CA - 2006; CB - 2007;