I'm late jumping in on this thread. As others have stated, several other American makers were using Lindner-sourced boxlocks as the basis for their guns. It some cases, like the first Donn gun Jeff used to own, there are no Lindner-marks on the gun though the details of the gun all shout Lindner. As Jeff points out the numbering sequence of the barrel numbers (as well as the gun's serial number in many cases) is consistent across multiple makers/retailers using Lindner-sourced guns. I am away from my reference materials but I can provide several examples that would link the serial numbers amognst these guns. But to why some guns have the Lindner marks and others don't? I'm not sure. I have some thoughts but I will leave that to another thread.
The German/Prussian connection appears to have been a very strong one as I noticed a curious similarity in the last names of many of the makers/retailers who sold Lindner-marked guns - Schaefer, Schmidt, Jakob, Daly, etc., etc. I do want to add while in most cases it appears that Lindner did nearly all the work and the retailer just put his name on the gun (i.e., Charles Daly), in several other cases (e.g., Donn, Schaefer, etc.), Lindner appears to have merely provided the guns in the white and the guns were stocked and finished here in the States. A close examiniation of these guns reveals real gun maker work that goes well beyond merely stamping one's name on the rib. Often the level of workmanship is just stunning.
I knew I should have bought that Donn when I had the chance :-).
Ken
