I found this list on the web and thought it would interest some of you. It's seems serial numbers were not model / type related but included everything done in order regardless. I dont know how accurate it is or if it is official but here it is anyway. Maybe those that know the true age of their own rifle could shed some light as to wether it is acurate or not.
First HW rifle produced: 1951
5100 Manufactured 1955
5138 Manufactured 1955
31151 Manufactured 1955
44485 Manufactured 1956
51322 Manufactured 1956
58446 Manufactured 1957
72243 manufactured 1959
76244 Manufactured 1960
99551 Delivered 1961
120662 Manufactured 1962
142447 Manufactured 1964
149423 Manufactured 1965
195863 Manufactured 1965
200000 manufactured 1966
241065 Manufactured 1966
395231 Manufactured 1968
296000 Manufactured 1969
309345 Manufactured 1969
322960 Manufactured 1969
332966 Manufactured 1969
333015 Manufactured 1969
333219 Manufactured 1970
346900 Manufactured 1970
357053 Manufactured 1970
373816 Manufactured 1970
375788 Manufactured 1970
400000 Manufactured 1972
401391 Manufactured 1972
423452 Manufactured 1972
469655 Manufactured 1973
480574 Manufactured 1973
496842 Manufactured 1973
512990 Manufactured 1974
583245 Manufactured 1975
600000 Manufactured 1976
612502 Manufactured 1976
623997 Manufactured 1976
624554 Manufactured 1976
670138 Manufactured 1977
671143 Manufactured 1977
702045 Manufactured 1979
741394 Manufactured 1979
778058 Manufactured 1980
777006 new in 1980
785538 Manufactured 1980
800000 Manufactured 1980
843636 HW35 from leather to nylon piston seal 1980
890268 Manufactured 1980
902189 Manufactured 1981
902315 Manufactured 1981
926011 Manufactured 1983
940000 new in 1985
943799 bought new 1986
1000000 manufactured 1983.
1000375 manufactured 1983
1001845 manufactured 1983
1003486 was delivered in 1984
1003516 Bought new 1984
1003582 was delivered in 1984
1003986 manufactured 1984
1007970 manufactured 1984
1011026 was delivered in 1984
1011108 was delivered in 1984
1016650 was delivered in 1985
1016823 manufactured 1985
1023310 manufactured 1985
1024914 new in 1986
1032802 purchased new 1986
1035801 1987
1036521 was delivered in 1987
1036528 was delivered in 1987
1040548 new in 1987
1041261 was delivered in 1987
1048169 1988
1066409 was delivered in 1987
1089152 Bought new Sep 1987
1099881 was delivered in 1988
1139541 was delivered in 1988
1139761 purchased new 1988
1233526 was delivered in 1991
1531173 2001
1162971 new in 1988
1178259 born 1989
1181401 was delivered in 1989
1181555 was delivered in 1989
1181588 was delivered in 1989
1182289 was delivered in 1989
1182580 manufactured 1990
1183140 bought new in 1990
1186081 manufactured 1990
1188451 was delivered in 1990
1195375 new in 1992
1288125 was delivered in 1993
1288752 manufactured 1993
1289991 manufactured 1993
1302969 manufactured 1993
1364279 was delivered in 1994
1370364 produced in 1995
1446049 HW77/97 switch from 25mm to 26mm cylinder
1459697 was delivered 1998
1538821 bought new in 2001
1551576 was delivered in 2001
1576934 was delivered in 2002
1606912 2003
1616583 produced in 2004
1634135 2004
1653441 Delivered 2005
1687223 was delivered in 2006
1690371 2006
1693047 new in Apr 2007
17320** Sep 2010#
1756120 2008
1767276 Bought Dec2010
1773086 Delivered 2009
1790356 Oct 2010
1802359 2010
1819808 new in Aug 2011
1831972 Delivered 2011
1832538 Nov 2011
1834705 Bought Jan 2013
1837081 2011
18560** Jul 2012
1856544 Sep 2012
1856662 Sept 2012
1856877 Delivered 2012
1867785 2012
1867893 Delivered Dec 2012
1875984 Bought Jan 2013
1878587 Bought Feb 2013
19045** 2005
1906032 2007
1907034 HW100 Full length changed to QF on 10/10/06
1909005 2007
1913451 Aug 2009
1914346 Manufactured Aug 2008
19178** Sep 2009
1918940 May 2010
1927208 Jun 2012
19308** Sep 2012
1930956 Sep 2012
1932093 Bought Jan 2013
1932998 Bought Feb 2013
1933020 Feb 2013
1933524 Bought 2013
1934822 Bought Jun 2013