Agree with shirlton, only need to take the stalks off, not the tails. It must be six weeks at least since my blackcurrants finished, you must have a late variety - do you know what it is?
Also, I tend to put the currants into a colander, and plunge that into a deep bowl of water, and if memory serves me right, you find that the wizened ones and the ones with a fair bit of stalk on float. so they can be fished out and dealt with.