US Test Lugers

In various reference texts, I have read that the original 1000 US Army test Lugers were:

a. consecutively numbered, (about 6100 to 7099)

b. skip serial numbers, to about 7500.

Anyone know the facts?


How is a 1900 American Eagle Luger (numbered in the above number range) differentiated from a US Test piece, assuming it does not have a "Germany" marking?


Thanks