I "dress" the ends of my springs. I grind the sharpend round and then polish them with 300 grit wet/dry paper. Make sure the end of the shrink is cut square at the bottom and I push it down a MM past the bottom so that when it shrinks it should be right on the edge. I leave a generous amount past the end of the guide, let it shrink REAL tight and then trim the making sure it tapers with the tip of the guide a little. It is common to use and adhesive on the guide as well, apply it after you have the shrink wrap perfectly cut and the oven/heat ready to go.