If you are going in to a piece of wook using top of bar, in a residential or in a "rural" (farmed/hunted) area, as far as I'm concerned you may as well be venturing blindfolded into an unknown and dangerous territory, using the wrong end of your equipment. Railroad spikes ... T-bar fence posts ... surveyor's PK nails ... car axles ... you just don't know. From personal experience, if you've ever experience a "straight-back" recoil (50cc at half throttle--worse than open throttle), I can guarantee you you won't go "saving time" with the top or tip of the bar, like you used to. PS, when it happens, *you (no matter how big you are (I'm 230lbs) you will *not be able to hold on ... it's something like an explosion ... unless you are strong enough to bend a crankshaft with your bare hands ... because a good straight back recoil will most likely break the chain, bend the bar and bar nuts and bend the crank, albeit only slightly -- but enought to finish the saw. Interior obstructions can occur anywhere in a tree exposed to people, including high up, as in hunter tree stands.
1. keep the chain sharp and the hammer down - a slow chain and/or a dull chain is a dangerous chain. Seems counter-intuitive, but a fast moving chain will chisel in, and work with you, it will even cut thru bolts ... OTOH a slow moving/ dull chain one will grab wood or object, and stick, and *BAM! spin the saw around on you real quick
2. hold on tight -- meaning feet on the ground and head, shoulders and hips out of the plane of the cut ... if the saw starts fighting you as in a plunge cut, fight back harder ... what ever you do, don't let the saw "get the upper hand."
3. think ... think ... think ... especially anytime you are going to lose sight of the tip, and anytime you are going to push in to unknown territory against the top of the bar
4. I think 056kid had a good suggestion ... with a small saw, short bar and a sharp low profile chain, try a shallow plunge cut ... go in 6" or so, WOT, bar angled down slightly to stay on the pull side, and then drop the throttle to just above idle, get ready, and change the angle of the bar a little, and let the tip "bite" into the front and top of the kerf, so that the bar will "walk" HAHA! back out the cut (instead of slam-back out of the cut). Using just enough throttle to engage the clutch, carefully walk (LOL!) the tip out of the top of the kerf, *keep *hold of the saw *all the way and especially as the tip comes out at the end, never mind that it's a small saw. Be WARNED!--even with a small saw and low profile chain on a small bar, at just above idle, the saw will seem to fly out of that cut. (Anyone know another way to create a controlled experiment whereby a newbit can personally "get" that "What da fudd!" idea, that kickback is an explosion and will happen so fast, your first thought after the fact, will be -- oh sh!t, this isn't going to be pretty ... where are all the pieces? your second thought will be ... ????, that could have been my last thought ... )