Why does the chainsaw bar get pinched in the wood?

The wood pinches the bar when the cut closes up behind the saw, usually from cutting a branch under tension or a log resting unevenly on the ground. Other causes include cutting too deep from the top without flipping the log, or bucking on a slope where the log rolls. The fix is to plan cuts so the kerf opens, use wedges on big logs, and cut the tension side first on bent branches.