I am in the middle of a large job removing 23 pine trees that are pretty tall and slender and so I bought a 32" bar and a couple of chains for my 660 as the 42" bar is pretty cumbersome. It has full skip chain on it and this may be the problem but the chain is really grabby. It sometimes will stall the chain and you have a hard time getting the chain out of the cut it is so deep in the wood. The chain is brand new Stihl chain. The guy at the saw shop talked me into full skip and I'm thinking I should have went for semi skip, or it may just be a bad chain. OH, both chains do this.