I've made some from scratch before, but the recipe that I used turned out just OK. The 4-5" casing will use a lot of venison in just 1 casing. The casing was water tight and not meant to dry or lose water. The recipe also called for it to be cooked in a water bath. You may want to try cooking some on your own. The large diameter casing should let you hand stuff & pack it tight.
I make mine with a seasoning pack from lem. Real simple, grind 5 ibs of venision mix with seasoning and a little water,stuff casings and cook in oven on 150 degrees 4-5 hours. I uses straight venison no pork or beef fat.