The American Machinist was published during those years, and you'd think copies of it would be all over the place ( and the Library of Congress I'd bet has a full set) , but the HathiTrust lists only one from the WWII years that's online, and that's only title searchable.. Their website lists a number of companies started during the war years.. You might try searching around under those business names, but you likely already know Hardinge, Bridgeport and Monarch. If you want to dig deeper, the Hagley Library has a lot of records of many businesses.

If you just want to wander down rabbit holes ( which can be pleasant) you might go over to Google Books' online offering of all the Popular Mechanics magazines...for example, there's one here on turret lathes , from 1942.