Can someone help me out. I would like to know about a Radom marking- VK inside a circle- just below the mag release button. It is about the size of the mag release button. This is a u series pistol. Also would like to know what are the numbers on the slide under the decocker and on the left side of the frame under the grip. They are different from one another and are not the SN which is matching in the 3 places. Thank you Bob