Eric, thanks for posting the US M1900 patent document US Patent 753414 granted in 1904.
Luger's patent activities were legendary, and somewhat controversial. In Europe, the German Patent Office (DPMA) gathers European and International patents in a wonderful resource that makes PDF files available of many of them.
Here are some of the Luger patents that lead to the USA filing:
Germany:
German patent #5318 was granted in May, 1901. It is essentially the same content patented in the USA 3 years later:
http://forum.lugerforum.com/attachme...1&d=1405686847
Switzerland:
Luger filed a series of patent protections in Switzerland as he developed improvements of the Borschardt and the initial M1900 Luger design.
CH 17977 is an early one resembling the Borchardt with improvements, granted in October, 1898 :
http://forum.lugerforum.com/attachme...1&d=1405687036
CH 18623 shows relocation of the toggle structure and recoil spring mechanism, granted January, 1899:
http://forum.lugerforum.com/attachme...1&d=1405687036
CH 21959 is essentially the M1900 patent, but done at the time of the Swiss contract sale and granted in May, 1900:
http://forum.lugerforum.com/attachme...1&d=1405687036
CH 31044 shows the new and improved extractor that made it into the later Luger pistols, granted May, 1904 in time for the Navy:
http://forum.lugerforum.com/attachme...1&d=1405687036
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It's sometimes difficult to form the searches, but you can locate other Luger patents at the modern DPMA's website. The patent searches can be done at:
https://depatisnet.dpma.de/DepatisNe...ion=einsteiger
i find this documentation fascinating...