That was my thought...cutting the locust. The only thing ive ever cut that can compare in hardness is dead dogwood and dead barkless elm. Its a Carlton chain. Bought new over the Summer for the 20" bar on my 261 which was a virgin. I bought two new after i bought the saw (i think it came with a semi chisel which i dont use) Ended up never rotating two chains as ive gotten into the habit of sharpening on site and/or just prior to use. I used to rotate two, but seem to have got out of that habit.