One thing is certain: Defining any "no name" "guild gun" as someone's apprenticeship project is way off the mark. I'd define a guild gun as any gun made entirely by outworkers, each applying their own specialty (stocker, barrelmaker, actioner, etc) to an end product, as opposed to a gun made entirely (or mostly) under one roof, by someone like Sauer or Francotte in Europe, or Scott or Greener in Birmingham. Other than guns from makers like Scott and Greener, the fact is that many Birmingham guns bearing a "maker's name" were in fact made by outworkers, just as were the European guns we refer to as "guild guns". The only difference is that, in many cases, the European guild guns weren't marked with a maker's name; rather, with either no name at all or with the name of the shop/dealer for whom they were made.

It's not that there may not have been "apprenticeship" project guns in Europe; rather, that there would never have been enough of them to account for all the no-name European guns we see even in this country--not to mention the ones that never left Europe.