I could maybe have mentioned this before but forgot. Despite all my ammo tests thru my first R9 - I did notice at quite a late stage that one mag presented the top round at a seemingly other than ideal angle - even if ''fiddled'' with. These mags worked OK most of time but, looking back - just perhaps it was the slightly ''rogue'' mag that might have given the odd FTF.
I measured the min dia across feed lips and came out at 0.310". I sent Eric and Karl this pic and a similar one, to ask about it. I was sent two new mags which are 0.320" across min dia of feed lips. This is the latest mag I believe.
Just mentioning cos it strikes me the wider feed lip dimension better ensures the correct angle of round presentation to the feed ramp. Might always be worth a check to see what mags you in fact have.
This pic is of the old mags .. one showing clearly its reluctance to allow top round to tip/present properly. GD's are shown here - the usual carry ammo. My 0.320" mags are just fine.