Thing 1: The metal mags use a skinny magwell: plastic takes more volume to be strong enough, so it's probably going to eliminate the magpul possiblity for us 10B owners.
Thing 2: According to my calipers, the wall thickness in the magwell area is about .140", and you need about .050" total for the magpul, leaving the sides of the magwell at about .1"... looks like enough to me. These numbers may be whacked, I'm working from memory and trying to hurry, always a bad combo. Bottom line, when I measured, it looked very do-able to open up the magwell and fit magpul magazines. I do have a 10B, an Armalite mag, and some Magpul mags for the measurements.
Gotta go, will be back if anyone wants to talk about this. Like I do!
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