I got a G30 3 weeks ago, and I've noticed when I break down the gun the barrel has 2 catches for the guide rod. One semi circled catch closest to the bottom of the barrel and a square shaped catch below it. The guide rod will sit on both, but after shooting it always rests on the square catch. Is this where the guide rod should sit? Why is there 2 places for the guide rod to rest? The semi circled catch matches the end of the guide rod perfectly why aren't they both shaped this way?