Don't buy Chinese stuff where non-Chinese options are available. They are not our friends. They are not even friends to their own people. My 2c.
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For the 12-18" hardwood stems and considering your current budget, the Echo 590/16" combo is about ideal. It will be fast enough and have enough grunt to not be frustrating, while still falling within your budget. The short bar makes sharpening go faster and keeps you from sticking the tip of the bar into the dirt and other things that you shouldn't be sticking it into.
Lately, we have been cutting those sort of logs up for firewood procesing, running a mix of saws - ported Husqvarna 543xp/13" at the low end, Stihl 261/16", Husqvarna 550MK2/16", ported Dolmar 5100sh/16", Stihl 400/16", Husqvarna 572/16", and Husqvarna 592/20". They all get the job done, some just get it done a bit faster. For cutting a downed log into pieces for splitting, where you make the same cut every 16" (or whatever your preferred firewood length is), having more power and grunt does make a difference.
For the big logs, the analysis is a bit different. Last year, we were cutting up a bunch of oddball sized logs that were dumped off by a tree service, including some in the >30" range, many being forked crotch pieces. That big stuff cut fine with the Stihl 400/25", Stihl 500/28", Husqarna 572/20", Dolmar 7900/28", and my ported Jonsered-Husqvarna 272/16". Yes, 16". Not everybody agrees, but I'd rather have a big powerhead and a short bar (and sometimes gearing up with an 8-tooth sprocket instead of a 7-tooth) and have to cut from both sides, than have a bar that I cannot lean on without pulling the revs way down. I find this works out to cut faster and be more productive, at least in my experience.
For really big stuff, there is a point where it just isn't going to be practical without heavy equipment. Some years back we had some white oak trunks that were rot-free (but not nail-free, sadly), and at the fat end used every inch of a 60" bar to cut up. They got cut with a Stihl 084/60" and 075/41" Once you flopped a 18" thick round off, it took a Bobcat with pallet forks to get the thing up-ended so we could then go in and quarter (or eighth or more) it so it would be small enough to put through the splitter. The labor and machinery needed to do that work was just not worth it, except for the fact we were having fun finally having a chance to use big CC saws and long bars in the way they were intended.
When I started out in the serious saw game almost 20 years ago, I came here to this site with a similar question to what you are asking. My Stihl 290 wasn't cutting it in the bigger wood, and I wanted to know how much more saw I needed. My question at that time was whether I should be looking at an 044, 046, or 066. I ended up buying a (6.3hp red top) Dolmar 7900 instead, and that proved to be the right choice. Ran a 20" bar on it most of the time, and a 28" for those instances where I needed more bar. I still have that saw and it pulls the 28" with regular, non-skip, chain just fine in anything I ask it to cut.
So in the end, what should you do? If your budget is not firmly limited to $400, I'd go find a clean used Stihl 046 (or 460), or Husqvarna 385/390, and set it up with 16-18" bar, and 32" bar (skip chain for the 046). Now, if your budget is truly limited in the way you originally suggested, I would go buy the Echo 590 and then cut, cut cut, and get good at sharpening, because a sharp chain will help you get the most out of what any saw has to offer, and if you're asking a 60cc saw to do 80cc saw work, it'll need to be sharp. See what you can do with it, and just don't cut what is too tedious to be worthwhile. I really think that the 16" bar and 24" bar (probably with skip chain) is the way to go for a do-all saw if that saw is the 590.
Eventually, you will either figure you that you need to add a bigger saw (90cc+) to your collection to get after the big chunks (bigger than most of what you showed in your pictures), or you will find you can get enough of the medium-large stuff with the saw you have and call it good, being a lot of money ahead of jumping right into the big saws from the get-go.
***************************************************
For the 12-18" hardwood stems and considering your current budget, the Echo 590/16" combo is about ideal. It will be fast enough and have enough grunt to not be frustrating, while still falling within your budget. The short bar makes sharpening go faster and keeps you from sticking the tip of the bar into the dirt and other things that you shouldn't be sticking it into.
Lately, we have been cutting those sort of logs up for firewood procesing, running a mix of saws - ported Husqvarna 543xp/13" at the low end, Stihl 261/16", Husqvarna 550MK2/16", ported Dolmar 5100sh/16", Stihl 400/16", Husqvarna 572/16", and Husqvarna 592/20". They all get the job done, some just get it done a bit faster. For cutting a downed log into pieces for splitting, where you make the same cut every 16" (or whatever your preferred firewood length is), having more power and grunt does make a difference.
For the big logs, the analysis is a bit different. Last year, we were cutting up a bunch of oddball sized logs that were dumped off by a tree service, including some in the >30" range, many being forked crotch pieces. That big stuff cut fine with the Stihl 400/25", Stihl 500/28", Husqarna 572/20", Dolmar 7900/28", and my ported Jonsered-Husqvarna 272/16". Yes, 16". Not everybody agrees, but I'd rather have a big powerhead and a short bar (and sometimes gearing up with an 8-tooth sprocket instead of a 7-tooth) and have to cut from both sides, than have a bar that I cannot lean on without pulling the revs way down. I find this works out to cut faster and be more productive, at least in my experience.
For really big stuff, there is a point where it just isn't going to be practical without heavy equipment. Some years back we had some white oak trunks that were rot-free (but not nail-free, sadly), and at the fat end used every inch of a 60" bar to cut up. They got cut with a Stihl 084/60" and 075/41" Once you flopped a 18" thick round off, it took a Bobcat with pallet forks to get the thing up-ended so we could then go in and quarter (or eighth or more) it so it would be small enough to put through the splitter. The labor and machinery needed to do that work was just not worth it, except for the fact we were having fun finally having a chance to use big CC saws and long bars in the way they were intended.
When I started out in the serious saw game almost 20 years ago, I came here to this site with a similar question to what you are asking. My Stihl 290 wasn't cutting it in the bigger wood, and I wanted to know how much more saw I needed. My question at that time was whether I should be looking at an 044, 046, or 066. I ended up buying a (6.3hp red top) Dolmar 7900 instead, and that proved to be the right choice. Ran a 20" bar on it most of the time, and a 28" for those instances where I needed more bar. I still have that saw and it pulls the 28" with regular, non-skip, chain just fine in anything I ask it to cut.
So in the end, what should you do? If your budget is not firmly limited to $400, I'd go find a clean used Stihl 046 (or 460), or Husqvarna 385/390, and set it up with 16-18" bar, and 32" bar (skip chain for the 046). Now, if your budget is truly limited in the way you originally suggested, I would go buy the Echo 590 and then cut, cut cut, and get good at sharpening, because a sharp chain will help you get the most out of what any saw has to offer, and if you're asking a 60cc saw to do 80cc saw work, it'll need to be sharp. See what you can do with it, and just don't cut what is too tedious to be worthwhile. I really think that the 16" bar and 24" bar (probably with skip chain) is the way to go for a do-all saw if that saw is the 590.
Eventually, you will either figure you that you need to add a bigger saw (90cc+) to your collection to get after the big chunks (bigger than most of what you showed in your pictures), or you will find you can get enough of the medium-large stuff with the saw you have and call it good, being a lot of money ahead of jumping right into the big saws from the get-go.