cattleman,
What kind of smoker are you using?
I just did a batch of summer sausage in my Smokette yesterday. My chubs are 2.5" dia. and about 8-10" long.
Here's my process:
1 hr. @ 100 with door cracked. No Wood.
1 hr. @ 100 add wood. Shut door.
1 hr. @ 130
1 hr. @ 150
After 1 hr at 150 I crank it upto 170 and keep it there until the internal hits 152- 155. This takes between 6.5 & 8.5 hours depending on the length & number of chubs.
My meat mixture for a 20 lb. is 18 lbs. of 90% lean ground beef (or ground venison with 10% beef suet added.) and 2 lbs. of ground pork shoulder.
This mixture gives me a sausage that is not greasy to the touch but is also not dried out.
I do, every once in a while do what joe b says, but I pull the sausages out at an internal of 145, and put them 170 degree water until they hit 152- 155.
The water bath joe mentioned is essential too. It keeps the sausage from getting that shriveled look and quickens the solidification of the fat so it doesn't continue to cook and run off after you remove them from the smoker.
After 10- 15 minutes in the water bath I hang my sausages in my kitchen to bloom. Once they hit room temp, the blooming process is finished and you refrigerate them.
Hope this helps some.