Model 51 was made between 1911-1947. Approx 11.000 12-bores, 3.000 16- bores and 20 20-bores were made.

serial year
16928 1884
20776 1890
26397 1897
35000 1901
37000 1902
40000 1904
45000 1905
50000 1907
55000 1908
60000 1909
65000 1910
70000 1911
75000 1912
80000 1914
90000 1915
100000 1916
105000 1917
110000 1918
115000 1919
119000 1920
120500 1921
124000 1922
125500 1923
129000 1924
135000 1926
136800 1927
140000 1928
143000 1929
145000 1930
150000 1931
152000 1932
155000 1933
157000 1934
160000 1935
163000 1936
165000 1937
167000 1938
170000 1939
172500 1940
173200 1941
175000 1942
184000 1943
185000 1944
187500 1945
193000 1946
199000 1947
205000 1948
212500 1949
219000 1950
225000 1951
230000 1952
232800 1953
234500 1954
235400 1955
236000 1956
236400 1957
236700 1958
237700 1960
238900 1962
240100 1964
241000 1965
242000 1966
242300 1967
242700 1968
242800 1969
243000 1970