Chain speed and 404 chain may have some to do with it. But, the Homelites had 20 years of commercial service, then another 20 years of me milling and cutting firewood with it. The 660 was showing signs of wear after about 2 years of milling and firewood duty. No where near the use the old 1050 got. Right now, if I try to dress the bars a new file just skates off the Homelite bar like it's hardened. The Stihl bar, the file cuts in much easier. The old Homelite bar is a hard nose also, and the Stihl has a sprocket nose, so you would think the wear level would be less on the 660. I think, for what ever reason, bars are softer now than back in the day. Super 1050, no load max 10,500, 100CC's. 660 13,500 no load, 92CC's