jeff just so you know all the church ladies including my mother and grandmother are cooking apple butter in a huge cast iron kettle over an open fire just down the road right now... i am talking a 30gallon kettle. remember the big wooden paddles they stir with???
22-250, are you sure they're cooking it in a iron kettle? I'd bet it's a huge copper kettle! The butter sticks to a cast iron kettle & causes it to burn. Copper or brass kettles are the norm for big batches of apple butter.