I stopped cutting flush to the collar and my oak splits dropped from 20 percent to almost zero
Last month I was losing about 1 in 5 big red oak limbs to tear out until an old timer in Duluth told me to leave a 3 inch stub and cut it flush in a second pass, and I have not torn a single collar since, so what is your go to trick for holding that second cut steady?
That three inch stub trick is basically the same thing my grandpa showed me on hedge apple limbs years back, he called it letting the wood tell you where it wants to break. What worked for me on the second pass was bracing my left forearm against the trunk so the saw does the work and my hand just steers, keeps the bar from wandering into the collar when it pinches. Worth a shot if you are still fighting that wobble.