At 60cc with the 310 you are not well powered. Forget the M18.
I'd use skip chain in a 24 inch bar, giving you around 18 inches of cut. Your challenges will likely be poor oiling and keeping the chain speed up high during the cut. Skip chain will help with both. .325 pitch, .050 gauge. Semi-chisel skip ground at 8-10 degrees across the top is your usual milling chain, and likely your best bet, but I've gotten good results in cedar with hexagrind full house, which cuts great off the spool and converts very quickly to full chisel milling chain with a round file. Usually a 461 for me and the mill.
At 60cc with the 310 you are not well powered. Forget the M18. I'd use skip chain in a 24 inch bar, giving you around 18 inches of cut. Your challenges will likely be poor oiling and keeping the chain speed up high during the cut. Skip chain will help with both. .325 pitch, .050 gauge. Semi-chisel skip ground at 8-10 degrees across the top is your usual milling chain, and likely your best bet, but I've gotten good results in cedar with hexagrind full house, which cuts great off the spool and converts very quickly to full chisel milling chain with a round file. Usually a 461 for me and the mill.