Two things, first on the US/UK generals front, do any of you listen to the excellent UK podcast "We Have Ways of Making You Talk"? It is done by the two most entertaining historians I have ever listened to. All about WW2, and they cover this topic exhaustively.
Second, on the wearing out of guns, I will say this as an anecdotal response . . . my battery (I would imagine like most of yours) is a mix of guns from different eras. English pre-WW2, Belgian pre-1980, Spanish post-1990, and very recent Italian. True, I baby the old Brits in terms of loads, and less so the others (although I shoot more gentle loads than any of them are made for), but my repair frequency has been just as high for the Spanish and Italian as the English.
Great discussion.
