One thing you learn a lot from, but may not want to do if you're only into antiques is actually owning repros bought as repros for reasonable prices, because then you see what's around, and what the differences really are. But of course you only want to do that if you can afford it, and if like Conogre, you are going to enjoy the repros......
AFAIK, screws, though often raised as an objection, are common on European arms and armour starting in the 1600s, and possibly so early in India, as well; surely in the 1700s. Of course, such screws are hand made, and are only traditional in certain applications, usually (certainly to adjust the nasal bar of a helmet, for instance), so seeing modern screws or screws in wrong places can certainly be a tip off to repairs or modern manufacture. It's all so dang complicated; that's why we sometimes find ourselves only able to say "I know it when I see it"..............those auctions took too long to load for my impatient self; I didn't see it
