I suspect this saw has been issued in various configurations to meet the different woods encountered in various regions. According to the manufacturer's website 3/8" is what it comes with today. Husqvarna Chainsaw 455 Rancher
While I don'f find the weight difference between a bar of 18" or 20" significant nor the weight of the additional chain. But swinging one around sure makes a diffference. And I'm pretty much a chicken with these things. Because trees fall or get blown down not to mention some pretty doggone big limbs, and I 've lost a half dozen or so to lightening; it seems like I'm having to cut something all the time. My son and son in-law will fire one up and get to it. Me; I stare at it a long time before I cautiously set the saw on the ground, step in to the handle and carefully start it up. Then I carefully cut whatever I'm going to cut from solid ground. And I prefer to keep the tip clear when cutting so the extra length comes in handy. I don't get around well enough anymore to do it any other way.
While I don'f find the weight difference between a bar of 18" or 20" significant nor the weight of the additional chain. But swinging one around sure makes a diffference. And I'm pretty much a chicken with these things. Because trees fall or get blown down not to mention some pretty doggone big limbs, and I 've lost a half dozen or so to lightening; it seems like I'm having to cut something all the time. My son and son in-law will fire one up and get to it. Me; I stare at it a long time before I cautiously set the saw on the ground, step in to the handle and carefully start it up. Then I carefully cut whatever I'm going to cut from solid ground. And I prefer to keep the tip clear when cutting so the extra length comes in handy. I don't get around well enough anymore to do it any other way.