I received my Stihl MS 310 on Monday. Haven't cut with it yet but have started it up, let idle, and rev'd a couple of times to make sure everything was legit. Before the Stihl I was using a Poulan Pro 295 (46cc / 20" bar) for all of my cutting. With a full-skip chain it could go through some wood. The time to get a bigger saw was now; so I did. Anyway, My 310 came with a 20" bar and full-skip chain and I also purchased a 25" bar with a full-skip chain for those rare times when a 20" is too small. This weekend I am most likely going to be cutting some Fir that is about 26"-30" DBH. I cut 2 stumps off with my Poulan a couple of weekends ago but it took awhile. What would you guys recommend I use this weekend as far as bar length is concerned? What would be most efficient: 20" or 25" ? I have used the search engine but could only find topics confirming a 310 can pull a 25" bar. How much power is lost with a 25" on a 310 as opposed to a 20" ?