If you call T/C, I suspect they would send you the screws you needed for free or for a minimal charge.
Duo-Rings make for a neat installation since there isn't scope base hanging over where the barrel taper begins. I also don't find them to be too high. I wouldn't, however, use them in guns with heavy recoil since the scope will probably slip in the rings and/or the base will loosen. They lasted less than 100 rounds before loosening on my 460 S&W Magnum even with Loctite. They're just fine though for low recoiling rounds like the 222 Rem., 223 Rem., etc.