Have finally come up with a real good chicken sausage recipe but it falls apart when you cut open the casing. Also would like to get some kind of a snap to the casing when biting into it. Can anyone help?
Crumbly sausage is usually due to not enough fat in the recipe and/or insufficient mixing of the sausage before stuffing. You need to mix it until it starts to get a little tacky/sticky, and even chicken sausages do require some fat. I make my chicken sausages with all thigh meat (no skin, but I don't trim much of the external fat) and that seems to work fine, as long as I mix the sausage until it gets to the tacky stage.
The main cause of crumbling is not getting a primary bind, for which you have to knead it well -- really romp on it. A stand mixer with the paddle is best. Too lean a grind also has an impact, but you can add all the fat you want and if you don't knead it, it just melts away & leaves crumbly sausage,
Additionally, cooking too... rough can make a sausage get granular. I try to cook sausage very gently, but I think the culprit here is probably it's not emulsified enough. Are you beating in a little liquid also?