Grendel mags?

[pinzgauer]

However, isn't it likely the top part of a loaded mag would bulge enough to hinder (if not prevent) insertion into the mag well, in addition to keeping a full or partially full mag from dropping free?

'Zackly right, Stan. All the folks speculating need to spend $14.50, get a pmag, and load it with Grendel. And watch it flex & bulge. :-) Stick int the mag well. Periodically spew cartridges & create jams. Then drop it and watch what happens. (speed ejection of the cartridges)

Now much of that is due to the narrow stack due to the thicker walls creating side pressure on the mag walls. But those walls are thick in poly mags for a reason! Without that you lose significant rigidity and strength.

I'm not saying it won't work for lower capacities, heck, they work as is in my rifles when loaded to 10 or less. But not something I'd trust, much less consider superior.

My gut sense is that there is some answer waiting out there with metal inserts possibly. But what is the advantage of that over just a basic, functional metal mag?