Game after game I seem to encounter the same thing. At about the time I have gunpowder and am researching rifling, the AI players (all but the lowest scoring ones) suddenly have Rifling, Artillery, Steel, Scientific Method, and Steam Power. I've literally been tied in research with them, only to see 3 or 4 civs with those 4 or 5 "Won't trade" techs on the list one turn later. Out of 60 or 70 Prince games, this has probably happened on 95% of them. I really feel like I've walked on a mine at this point as I have a tech disadvantage that I have zero leverage to barter from and I'm defending against Artillery (the pretty much game-ender) with Musketmen and a few Riflemen; I regularly lose 4:1 units until - and IF - I make it over this hump. My "pleased and friendly" neighbors won't share and now I have the top one or two warring with me and bringing vassals in as well. Does this happen to others? I'll confess that I don't like Prince level. Is there an obvious flaw at this point in the game I should try to deal with?