Welcome Mike!
This is probably NOT a test gun, although anything is possible.
Can you tell us any markings or proofs on the gun?
Proofs? (see on your left under tech information if you came through
www.lugerforum.com) Tell us what and where proofs and markings are located. You said no others? I beleive there should be some, but older ones are out of my purview.
There are forms in this section, where you can print out and then write down pertinent information.
Are there any year or letters are stamped on the top of the receiver? {{I expect not, but ask anyway}}
Can you provide pictures, to include side, top, etc?
It should be 30 Caliber and is most likely a commercial model.
What do the toggles look like? {The things you pull back to load it.}
Ed