When the No4 Mk1 started production in 1941, the top surface of the long bolt lug, the handle, the knob and about 1" of the bolt body at the bolt root were blued. The remainder of the bolt body was left in the white.
Boltheads were blued with the bolt face left bright.
This goes for BSA, Fazakerley, Maltby, Longbranch and Savage.
Longbranch and Savage used the Dulite bluing process, which can look like Parkerizing when it gets old and tired, but isn't.
On the British side, production was rushed and unimproved early-WW2 No4 rifles are most often found with thin, faded blue. Some of this suggests Parkerizing, as well, but isn't.
Parkerizing alone was tried on an experimental basis by the Brits in WW2---or so the book says---but I have yet to find one.
Parkerizing under black Suncorite paint was introduced on the No5 rifles during the war---but the bolt finishing pattern was the same as described above.
-----krinko
