Lithgow Rifles Survey

[5thBatt]

Yep look at your survey, the second half of B prefix have barrel dates in the second half of 1941/early 42, C prefix barrel dates are nearly all 1942 but most are on 41 actions, D prefix fall into 1943.
ignore action dates they will only confuse your survey, they only tell you when that receiver was made & nothing to do with when a rifle was assembled.