You don't shoot bottle caps. You shoot targets to get bottle caps.
Oh right , Its been awhile since iv played my copy of Res Evil 4, I don't recall having any problems shooting them regardless
THE BEST METHOD to run PSX games (and everything else for that matter) is via Retroarch - http://buildbot.libretro.com/nightly/
If you have any questions on how to set it up on Windows please feel free to ask, its very easy.