BJ, I had a spot where the cortex was rubbed off and had a slight angle. I used about a baseball sized hammerstone and gave it a good lick. I have used bi polar sometimes to open up the hard round nodules, Watched James Parker give a demo on bipolar reduction, as usual he made it look so simple. Some of the hornstone type nodules can be real tuff to get into. I believe the really thick cortex absorb your blows like a sponge.
The point of the month was a big influence on my knapping, I couldn't hardly wait for the new style to come out every month, I truly tried hard to help keep it going by always entering something and participating, I learned so much in my earlier yrs from the knappers and their style of replicating points. I really miss POM. Traveling to lots of knapping has also helped in learning different point styles and methods. Bob