I have a new VP9 with only one shooting session and 150 rounds through it. During that session I noticed a couple failures to lock back on empty that I attributed to my grip.
I have been working it dry and while working reloads have found it will intermittently fail to lock back on an empty. I have isolated the problem to a single magazine, and have actually swapped springs and follower from a functioning magazine which did not help. The issue appears to be due to the actual magazine body. I have inspected the inside of the body and found nothing the follower could hang up on and it seems to insert the same as any other magazine. I see nothing out of the ordinary on the outside.
I contacted HK and they offered to swap the magazine out for me which is generous. Before sending it in I wanted to know if anyone else has noticed this problem. I have one friend who carries a VP9 as his primary pistol, when I mentioned this to him, he noted that he also had the issue with a certain magazine. He cleaned the gun and it stopped, but it was also a single magazine issue for him.
I guess I am wondering if HK has changed specs on the magazine body or internals as Glock so famously does on the fly.