Think of chains like this: Small (>50cc) powerhead : .325 because the teeth are smaller they require less power to pull Caveat: some 55cc and ported 50cc saws can pull 3/8, but only on short bars. Large powerheads : 3/8”. If it can take a bigger bite, let it, otherwise the saw is wasting its power. 3/8 will be more smooth than .325 in big wood. .325 will be less grabby and less likely to throw a chain in small brush. Semi chisel is good when the wood is already down on the forest floor, has been dragged, or low on a tree where it is dirty from wind blowing grit into the bark. It holds an edge longer than chisel. Good edge retention, like an all season tire. Chisel cuts faster than semi chisel, but doesn’t stay sharp as long. It’s great for clean, green wood and will stay sharp for a good while as long as the wood is clean. It will require more frequent sharpening if used in dirty wood. It’s like a summer sports tire. Square file is faster yet, but dulls even more easily. It is difficult to hand sharpen, necessitating a grinder. Most people don’t even know about it. It’s like a drag strip tire.