Just seen this thread and feel for you with the stolen equipment and the XSV Axe. These were limited to 44 in the whole of Europe, we have 3 of these on our team and another couple have sold theirs. Whilst these dont show any kind of serial number, they are all slightly different. When me and a friend got ours we did compare them and you can see the print is slightly different - this is so slight that without having 2 guns together you wont actually be able to pick it out.
I hope you do get your gear back and catch the thieving scumbags !!!!!