The temp sounds a little high.When I made some I used the thermal processing for Polish sausage found on this link.I also use this method for regular link sausage and it has never failed me yet.I usually keep smoke going for the first two hours,then just heat after that until the product is finished.

http://www.ag.ndsu.edu/publications...rt-and-practice-of-sausage-making-fn-176

Too high of a heat totally ruins it.Low and slow works best.Anymore when I make sticks,I just se my jerky gun and dehydrator.It has a snack stick tube and you don't have to stuff it in sheep casing,which is really delicate work

~Molɔ̀ːn Labé Skýla~
As Bob Hagel would say"You should not use a rifle that will kill an animal when everything goes right; you should use one that will do the job when everything goes wrong."Good words of wisdom...............