If WinRAR or 7-Zip reports a "Checksum error" or "Unexpected end of archive" specifically at part13, that individual file is likely incomplete.
You must have every single part (part1, part2, ... part13, etc.) in the same folder to extract the game successfully. You cannot extract part13 individually. CallOfDutyInfiniteWarfare.part13.rar
If you are getting an error about this specific "solid piece," it usually means part13 is corrupt or missing. Because solid archives treat all parts as one stream, damage to a single part often prevents the extraction of any files that follow it in the sequence. If WinRAR or 7-Zip reports a "Checksum error"
Are you seeing a when you try to extract the file? CallOfDutyInfiniteWarfare.part13.rar