@strenkarosa I’m thinking it was the heat. The same thing happened t me my last batch. I held at 170 for 7 hours. I was almost at temp, but it was 1:30am and I wanted to go to sleep. I bumped it to 210 and be for you know it, half the casing split. DANG! I originally thought it was because I was using casings which had been warmed in the past and then dried out because they were not used. I think they were stuffed too tight and the temp was too high. The cases split length wise on the sausage, with a v-grove shape about 3/4" deep. I let them cool and to my surprise, the gap had completely closed once the sausage was cool. They still taste great, however not to be given away to the neighbors.