Place 7 cups washed pyracantha berries in a very large pan with 5 cups of water. Simmer uncovered for 20 minutes. Strain through a cloth.
Measure 3 cups berry juice, 1/2 cup lemon juice and 7 cups sugar into a very large pan. Over high heat, bring to a boil, stirring constantly.
Immediately stir in one bottle liquid pectin, bring to a full rolling boil and boil hard for one minute, stirring constantly. Remove from heat, skim off foam and pour into sterilized glasses. Cover With 1/8 inch melted paraffin.
Prepared berry juice may be refrigerated or frozen prior to making jelly.