Pyral, I have used the damp washcloth/hot iron on gun stocks, and it works great.
Just go slow, only putting the hot iron on a DAMP washcloth for 10-15 seconds at a time until you see how much the grain will be raised. My first attempt I over-did the hot iron part, and discolored the gun stock. Go slow, and it will work fine. Also, dont use a dripping wet cloth. I wring out the cloth, and go from there.