Sort beans carefully to remove stones, damaged beans, and debris, then soak 4 pounds of dried pinto beans in cold water for 12-18 hours using 3 cups water per cup of beans.
Wash canning jars in hot soapy water and rinse thoroughly, then keep hot in a 200°F oven until ready to fill, and prepare new lids by placing them in hot water heated to 180°F.
Drain and rinse soaked beans thoroughly, then place in a large stockpot with fresh water covering beans by 2 inches and bring to a rolling boil.
Boil beans for 30 minutes until tender but still firm, maintaining water level and skimming foam as needed, then drain beans while reserving the hot cooking liquid.
Check pressure canner for proper operation, add 2-3 inches of hot water to canner bottom, place rack inside, and begin heating canner while preparing jars.
Pack hot beans into hot jars leaving 1 inch headspace, add 1/2 teaspoon canning salt to pints or 1 teaspoon to quarts if desired for flavor.
Cover beans with boiling water or reserved hot cooking liquid maintaining 1 inch headspace, remove air bubbles with plastic tool, and adjust liquid levels if necessary.
Wipe jar rims clean with damp cloth, place hot lids on jars, and apply screw bands fingertip tight, then place filled jars on canner rack.
Lock canner lid in place, heat until steam vents steadily for 10 minutes, then place pressure regulator or close vent to build pressure to 10 PSI for altitudes 0-1,000 feet.
Process pint jars for 75 minutes or quart jars for 90 minutes at 10 PSI, adjusting pressure for altitude (11 PSI for 1,001-2,000 feet, 12 PSI for 2,001-4,000 feet, 13 PSI for 4,001-6,000 feet, 14 PSI for 6,001-8,000 feet), then turn off heat and allow canner to depressurize naturally before removing jars to cool for 12-24 hours.
