I haven't noticed any cracking in mine.
I'll tell you, though. I'm pretty impressed with them. Take a look at what Buffman did to them on one of his YouTube videos. He essentially froze fully loaded magazines, and dropped them lip downwards from about 10ft up onto a concrete floor. They resisted multiple drops before failure. I don't anticipate abusing them to that extent. If they can drop and survive getting thrown around, they're good enough in my book.
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