few years back one of my customers requested assitance with a big old Box Elder. He and his partner had whittled it down to the point of being a 8 ft tall 4.5ft dia stump. these guys were running 18" units Poulan and Craftsman. They knew I had large saws. They were going to pay me for my time , so why not. I found every manor of chain wrecking items in that stump, But the absolute kicker was the "t" post dead center. I went through six 115dl chains - destroyed 2 and hand sharpened rest before the end of the day and that stump was gone.