Im going to start this on PowWow and move it to "how-to" soon. Hopefully thats alright with MGMT.
Grizzly 160 and 190 grain heads are harder steel and are harder to work with. The first step is to drasticly change the angle of the cutting edge. Imagine drawing a line from the cutting edge through the top of the ferrel. This is the pitch you will be trying to achieve. The top head is factory and the lower is where you want to be.
I use a 12" file and clamp it down like Charlie Lamb in his ww sharpening video. Notice how I grasp the head so that my index finger drags the table. This creates an exacting angle. I now push toward the point till I remove enough material to get the long angle. This takes quite awhile so be patient.
Now, once you've achieved this angle.
You will want to take the burr off the opposite side with one or two light strokes on the back side. From this point we will move on to a "quality" course wetstone then on to the fine wetstone.
Remember: keep the angle exacting by locking the head into your hand and dragging your finger tip in the same place every time you stroke.
Once the course and fine stones are used sufficiently, I move on to a sheet of 600 grt sandpaper on a clipboard using some light oil and pushing forward with each stroke.
Once the blade is polished slick with the 600 grt, I move on to ceramic crock sticks. This is the final step unless you wish to stromp the blade on leather.
I know that this a lengthy process that most guys just wont want to spend the time on. The one thing about the Grizzly is that once you've completed these steps and have achieved a shaving sharp edge they will remain forever easily sharpened. The head I shot the pig with last week was still shaving sharp after going through two rib cages. I hope this helps. Just keep an unchanging angle while sharpening and most of all be patient! Good luck. If you have questions then ask away! CK