Magpul’s Mega-Capacity Drums

Don't think they'll fit a Polymer80 lower. The front of the P80 magwells are horizontal, rather than angled upward, and the molded ridge on the straight 'riser' of the magaine looks like it would prevent seating.

I imagine the ridge could be ground off without impairing fit or function; does anyone have real-world experience with using these in a P80 lower?