I read the article. I would use the word, "break", rather than "rupture" in the title. Second, the user never stated, but I inferred, he was using that vertical grip to handle a large part of some rather nasty recoil. I have no idea on how hard he torqued down his attaching bolts, or if he had them butted up against the forward cross rail, to most efficiently transfer recoils forces from the weapon to the accessory. I do this religiously for everything on rails, including sights and scope. Finally, I don't know if he was checking for "slop" or movement during the first few rounds fired with any new gun.
I have the Magpul AFG2 angled foregrip on the pump handle first and foremost as a hand stop. Second, it provides me multiple ways to grasp the forend due to my carpal tunnel. I have a few tacticool shotguns, all with plastic rails, and do NOT have vertical grips on any of them to use as a mechanical advantage in operating the handle, or handling a big part of the recoil.
Based on the very little said in the article, I suspect the shooter was making a couple of careless moves that bit him around shot 10. I will be doubly-careful when trying mine out, however, since I suspect this was a cascading series of user errors.
Oh, I paid regular MSRP for mine (still unchanged from long ago), and the sling is a Magpul MSR2, which lets me unclamp the front of the sling, and clamp it to a D-ring near the rear, for single-point use.
Thanks for the heads-up, I will double-check everything before I shoot, and while shooting. My suspicion was it was the old rock-and-slide that done in the plastic.
I read a review that said a good idea is to attach a metal spacer rail to the plastic one before putting on the foregrip.