At the moment all I have is a 260 with an 18' bar, bucking firewood on a foresty landing over the weekend. Lots of the trunks were at least half again as long as my bar...reducing cuts, borecuts and a WEDGE are very handy.
...boy all that nasty gravel the ants carry up into old trees, and all the dirt on the trunks from being dragged to the landing, I have never seen a chain wear out so quickly! I had a brand new RM chain...used about 3/4 of it in four hrs!
One of the handiest short bar techniques is boring in through the back of the face cut, fanning out some of the bulk of the wood in the middle of the tree (and gutting the hinge in the meantime) It allows you then start your back cut on one side and walk around the back of the tree setting wedges as you go and finish the back cut in one go, or if its a slight head leaner, bore in from either side, leaving the strap at the back to cut last.
You can get a tree like 2.5 times as wide as your bar is long...cutting the face accurately takes a bit to get right though, matching the cuts on either side.