The problem is both the mag release and the magazine.

I'm hitting my middle finger with the mag release half the time. I wish they would have gone for a reversible mag release over a full time ambi.

The mag release has a nipple that engages into a ledge formed on the magazine. This ledge is created by welding a piece of metal to the mag body. One my mags, the ledge isn't at 90*. It actually has a slight slope, which makes releasing with the right hand traverse longer and against gravity. Releasing with the left hand is super easy as it traverses shorter and with gravity. Some quick work with a file to radius the slope and offset the angle and now it drops perfectly.

I'd suggest you take a careful look at you mags with a square.

Also WTH.  MAP pricing on mags is $44. I guess they don't want to sell many of these guns. I'm not paying that kind of rate especially if they don't bother to make them right.

Speaking of the 509 I went down to the FN Pro Shop today and got to handle one. I liked it a lot. If I got to shoot one I'd probably end up buying it. But I do think I am going back to get the fn9 compacts in FDE. I think it's a gun I'd enjoy. Plus I'm bored with all my Glocks.

Three free mag promo just started
FN 509 three free mags promo

screenshot of email from FN

Doesn't really help those of us who bought the gun a week ago.