Depending on your game climate (I've heard of feeding issues in REALLY dry and sandy areas being fixed by a bit of lube in the rubber) it'll matter what you do/don't lube.
I've had feed issues with my mid-cap mags since I got them. VERY dry climate here and yet my solution has been one drop before the mag is filled each saturday night before the game. I tried that shit in my barrel and never again will it happen. I really cannot say that it helped in anyway at all. The only other solution I got was to keep my mags in zip-lock bags... Not happening.