Build yourself a bucking crib (do a search on Arboristsite, there are some good threads about them.)
Cut the logs into sections that you can physically handle (length depends on tree thickness). Pick up or roll the newly cut sections onto your newly built crib. Heck of a lot easier to cut than to cut, roll, cut, etc.
My crib is short, the logs only sit about 6 inches off the ground when they are on my crib. Because it is short, it is also easy to hoist the logs on. The log sits on the crib and hangs off both sides. I cut on one side, then the other, then cut what's left in half. Usually works out to be equal lengths for all pieces, but it isn't rocket science here. My cut pieces can now be used as props also to hold up my next log. Get the picture?
Sometimes you have to cut, roll, cut, but I hate doing it this way. Much greater chance of hitting dirt with the saw and I tire out faster this way. My way, I can make 3 cuts right away while the log is on my crib.
I don't understand why your bar tip sprocket is getting jammed (if I understand you correctly)? Is your chain on too tight? There are quite a few places that rent Stihl saws, why don't you go rent one. This way you will know if you like the saw before you buy it. Taylor Rentals around here have Stihl saws for rent.
Be careful when cutting with the tip of the bar, that is how you get kickbacks and higher chance of pinching.
Having a saw/saws that are running 100% efficiency is very important. If your saw is not performing, that makes it much harder and sllllloooooooooooowwwweeeer.