I have question about my Boker Rhino. I've been carrying it every day for about two weeks, using it for everything from opening boxes to food prep to whittling'. My question is, does anyone know, or is there a place I can go to find out what the factory grind angle is. It's about ready for a touch up. I have a Worksharp Guided Sharpening System to use, but should I use the 20 degree guides or the 17 degree guides? Thank you