Place the autumn olives in a pot with a bit of water. Use 1 cup of water per pound of autumn olives, or for the full recipe, 3 cups water and 3 lbs autumn olives (10-11 cups fruit).
Bring to a boil and then cook the fruit with water for 1 to 2 minutes, until it falls apart.
Strain the fruit through a fine mesh strainer, working the fruit with a spatula to push the pulp through but keep the seeds in the strainer. You should have about 6 cups pulp.
Place the strained fruit back into a jam pot, bring it to a boil, and add the powdered pectin. (Don't add the sugar yet.) Boil the fruit pulp and pectin for 1 minute, stirring to incorporate.
Add the sugar, stir to incorporate, and return to a boil for 1 minute. Remove from heat and ladle into prepared jars, leaving 1/4 inch headspace.
If canning, process in a water bath canner for 10 minutes (15 minutes above 6,000 feet in elevation).
Cool jars completely on a towel on the counter, and check seals. Store any unsealed jars in the refrigerator for immediate use. Sealed jars will keep on the pantry shelf. Refrigerate after opening.