If you have a motorized dremel tool just use a small sand paper roll on the arbor to lightly smooth the roughness off of the ramp. If you don't have this tool you can do it by hand with a small wooden dowel with fine grit emery cloth rolled around it. Just smooth it out a little at a time, try it out, then smooth it out a little more when it starts to work better stop & let it work in as you shoot.