Prepare boiling water canner. Heat jars in simmering water until ready for use. Do not boil. Wash lids in warm soapy water and set bands aside.
Combine berries in an 8-quart saucepan. Gradually stir in the pectin. Bring mixture to a full rolling boil that cannot be stirred down, over high heat, stirring constantly.
Add entire amount of sugar, stirring to dissolve. Return mixture to a full rolling boil. Boil hard 1 minute, stirring constantly. Remove from heat. Skim foam, if necessary.
Ladle hot jam into hot jars, one at a time, leaving 1/4" head space. Wipe rims. Center lids on jars. Apply bands and adjust to fingertip tight.
Place filled jars in canner ensuring they are covered by 1 to 2 inches of water. Place lid on canner. Bring water to a gentle, steady boil.
Process jars for 10 minutes, adjusting for altitude. Turn off heat, remove canner lid and let jars stand for 5 minutes. Remove jars and cool. Check lids for seal after 24 hours. Lids should not flex up and down when center is pressed.