Helping a friend out. She has a CAI import 7.63 Mauser 626XXX serial number, all matching. It has markings under the barrel just ahead of the chamber. I believe a 4 and an N or Z and one of the funny looking Bs with an odd, curving vertical stroke. On the right side of the slide just ahead of the ejection port are a pair of Asian characters. one looks like 77 and the other looks like a 4 section square with legs. They are side by side and the 77 is slightly smaller and to the left of the square. Gun has the small ring hammer and adjustable 50-1000 sights. Any help is appreciated.