No intent to hijack the thread from the original reviewer, but I just wanted to add my results to this existing thread (keeping info all in one place, for now).
Not at all, it makes perfect sense.
Turns out that while the documentation may say it takes Beretta mags, it doesn't actually take Beretta mags, at least not the official ones.
The two I bought are Beretta made and they work in mine better than the pro-mag that came with the rifle.
Looks as though these things are going to vary in quality, dimension and reliability.
Now we all know why they are a $400 gun.