My M&P 40 full-size ever since I got it just ejects brass absurd distance. My local indoor range has 6 lanes, #6 being all the way to the left wall and #1 being all the way to the right. The first time I took this M&P shooting it was ejecting brass off the cieling but also throwing it all the way from lane #6 down to lane #1. I could see how this could be a nuisance or distraction to other shooters. So I swapped the factory 16# recoil spring with a 22# ISMI recoil spring. This didn't really seem to make as much of a difference as I thought it would. I was at the outdoor range and it was still launching brass sky high and and around 12-15 ft. away my 4-5 o'clock. I think it was hitting some of the range officers who were standing around back behind the yellow line because they came over and said something and put up a brass screen next to me, which had no effect whatsoever because the brass just flies over the top of it.

Honestly it doesn't really bother me, I like the gun a lot, but it is annoying that it makes it difficult to collect my 40 brass. I don't know if this is just normally how this gun operates? Does anybody else's do the same thing? I've been shooting 180 gr. Remington, Federal, and Winchester.

I would remove the extra or snd inspect the extractor face, spring and channel to see if anything was damaged or looked odd.  You could also swap for a new extractor &  spring to see if that helps.

S&W told me just keep shooting it until it's broken in and it should stop doing this. I've got at least 500 rounds on it so far so I'll probably try and shoot another 500 and then see where it's at.

I think that’s a bullshit answer from S&W.  

None of my M&P pistols have ever needed any sort of “break in”.

And 500 rounds is plenty of shooting to knock down any burrs or surfaces that would be subject to “break in”.

I don’t think your pistol is going to change performance within the next 500 rounds.