I always remove the bar and wrap it in cardboard. I make sure the box for the saw is just big enough for it to fit in, w/o being able to move around. I usually make sure the bottom of the box is double thickness. You're gonna need some flat cardboard to cut to size to fit the bottom of the box.
I use foam peanuts and bubble-wrap extensively. Both are relatively cheap to buy, and will assure good protection for the saw. And, it should go w/o saying, no gas or oil in the saw. I wrap the saw in bubble-wrap with plenty of strapping tape.
When it comes to sealing the box flaps, I prefer to use Elmer's Glue, rather than tape. Glue will make the box more rigid and sturdy. Once the box flaps have been tightly glued, I still use tape to seal the seams. Don't scrimp on the tape either. Buy good thick shipping tape.
When it comes to addressing the box, I use clear tape over the name / address it's going to. It protects the address from any fluids that might end up on the box during transit.
And, I always pay for tracking, whether the buyer wants it or not. I guess USPS now offers tracking at no add'l. cost. I would assume that UPS and FED-EX probably now do the same.
I've done the above many times, and have never had an issue with shipping and getting the item to the buyer in one piece.
I forgot to mention, that Home Depot sells box that are very economically priced. They also have heavy-duty boxes that cost just a bit more. I prefer to use a new box, vs. a used, worn box that has a bunch of writing or printing on it. Nothing like receiving a box and it looks as if it's been thru 3 or 4 moves, or was used to store stuff in. Not a good thing.