tough collagen casings

[tommix]

I just made my first batch of snack sticks using one of Len Poli's recipes. The flavor came out real good but the collagen casings were tough. I used 21 mm smoked collagen casings and smoked the sticks until it reached 150 dgrees F.

Is that just the nature of these casings? What casings would you suggest for making snack sticks. I loved using the collagen casings, very easy to stuff with no breakage.

Thanks........Tim