I had the same experience a couple of weeks ago, I called Kvar they told me they receive it from Russia that way. It is supposed to prevent rust, but I didn't know that and was horrified when I opened up the box. I cleaned it off and its been fine.
Yes there is an Arsenal Stamp on the very back of the receiver on the same side as the scope rail. I will check the ports tonight, just finished the pistol grip I am trying to get the Saiga Internation Stock Adapter to fit. Even more frustrating I fired buchshot and slug rounds on setting two because the advertisement led me to believe that there is a semi and single shot mode so if it cycled its on the right setting.