Yes, I agree. Likely something wrong with one of the lugers and it was put together this way, or even someone sitting around the camp or something. Not likely a rearsenal, as they would not send it out with wrong numbers (too many parts around, even at the end of the war not to put on un-numbered parts and renumber them).
The price you paid was a tad bit high, not counting the holster, with the holster you did just good.
Geladen (that doesn't look right) was the word for safe or fire; it is covered in the FAQ which you can find in the new collectors forum and I think on the top of the page
Welcome to luger collecting!
Ed