OK, the very first post of this had the hint that I learned to prevent or make the kickback less which was:
Wiggle wobble the bar just a little as you bore in. It works. The reason I did a bore cut was that the bar would be pinched coming down from the top, and I wanted to come up from the bottom instead of wedging and possibly sawing dirt. There was about an inch of clearance between log and dirt on the bottom. The Doug-fir was about 22 inches diameter at the cut, and 90 to 100 feet long...so rolling it over was not an option. I was being tested, and decided to do it that way --the testers consider it a more advanced way to cut. They were the ones who mentioned wiggling the bar as you bore.
So, since the pinch would happen on the top, I started on the top just a little, worked it over the far side a ways, came back and went down on the top till it started to close up, ran the bar down the nearside, wiggle wobbled a bore cut into the bottom and came up. Log parted, log bucked. Just one of many ways to buck a tree up. Not necessary every time. I thought the wobble wiggle was a good thing to know. Trees are different, saws are different, we all have different abilities. I used Twinkle the 440, 28 inch bar, and full skip round file chain-- but only have a half wrap handle.