If you roll the sausage out to add filling ingredients, don't roll too thin, as it will tear easily. I roll mine out to about 3/8th of an inch.
Also, when you roll it back into log form, chill for a while in the fridge to firm it up.
And, like others have said, it needs to be pulled no later than 160 f. internal, or it will get to be like sawdust.
That's the fatty world as I see it.
Now, if only I could get that chicken skin crisp every time...