Fresh helps to narrow the field. Germany has over 200 sausages with most of them being in three groups - Mettwurst, Teewurst and Bratwurst with the first two being Rohwursts which are raw sausages. (Roh = raw & wurst = sausage) So this would probably put the sausage over in to some sort of Bratwurst but you said it contained beef. As a rule in the day, bratwurst were to contain veal and pork so if veal is what you meant then its highly likely it was some sort of bratwurst. If beef is what you truly meant then it could push itself maybe toward a Knackwurst which uses chuck roasts and things like that in it. Knacken = means pop and wurst = sausage So this sausage was meant for grilling and pan frying after a quick dip in a water bath or beer bath and when made proper the casing is meant to pop when its finished and allow juices to flow. Being in a pinwheel doesn't really say much about the type sausage since this is totally up to the maker. For cooking purposes, it might be easier to not link the knockwurst since it is so juicy. If your father can remember the texture then this would also be a good thing to key on. For instance, since bratwurst contained veal, it was minced into a coarser grind than knockwurst which is ground into an emulsion similar to a hotdog wiener. These are general rules and its not to say everyone HAD to abide by them but the important thing to understand is the changing little things like the grind, the meat type and/or proportions, the change of a few spices and proportions makes a huge difference on the end product and its name. Of course if your grandfather's last name is Scholtz, there'd be no problem figuring this one out. If your father remember any of these little defining things then we might can narrow it down some more.
