Well, I use a very different recipe from that, as you may have read.
But even so, I think you are using too much water. When I asked a similar question, we got to why Oxford sausages are called bangers. it is because there is so much water in the mix that the skin bursts.
I think that this is what you have happenining.
I do not use more than one fluid ounce of liquid to eight ounces of meat product. But my sausages are ultra low fat, and designed differently. Oddley is probably your best bet on this, But I suspest it is the amount of liquid that is the problem.