Yeah, I hit a nail at the ground and an old full metal jacket rifle slug. I expect we'll hit some more. There was a cable or a wire in the biggest crotch 28 feet off the ground. I'll split it and see what's there. I have found entire woven fences before in trees that looked perfect from the outside. Often find metal. Often bullets.
One time my brother milled a big tall tree. the bottom limbs (crotch) was over 30 feet off the stump. He hit a very old style spark plug from a car engine with the plug wire stuck on the wrong end. I thought maybe an electric fence wire insulator. But who knows how it got there. Also have to be careful about old tree stand spikes that the hunter's put in
Thanks for the warning. I'll probably risk a blade or two.