How many Mossberg 46b manufactured?

Good question- not sure that anyone has an exact answer. The 46 B was made from 1938-1940, and production resumed after WW II, 1945-1946. These rifles did not have serial numbers (not required until 1968), so it is not certain that anyone has precise numbers. You may check with Mossberg- they are likely to refer you to the Mossberg Collectors Association, through havlinsales.com. Vic Havlin and his wife Cheryl run the Association, are very nice and knowledgeable folks- contact them.

PS- the 46B is an Excellent target rifle. I have one, it shoots better than I do.