I like the advice given so far. I'll try not to post more of the same. (I'll fail a bit!)
GET the bullet puller, tear down your test rounds and look to see if you've marked up those bullets. If you have a tiny, tiny trace of a ring that you can visibly see with the eye, that's plenty. I don't think it's too much if it's just a light, visible trace. If you are ALTERING the shape of the bullet and giving it a new waistline, that's FAR too much.
Agree 100% that your biggest worry is too much mouth flare, crappy brass and bullet setback. Guard against bullet setback in ever any, ALL semi-auto handguns and your world will be better for it.
Test for setback simply by pushing a loaded round (or a dummy) bullet-first in to the edge of your bench. Give it a firm push-- more than a harshly jacking pistol slide would do in live fire. That bullet can't move, not even a bit. If you have that, you are in good shape. It's important to me to sort my brass so all my brass GIVES me the same feel for exactly this reason.
Two suggestions: S&B brass seems to be quality brass but those crazy folks make super-slim primer pockets making them a royal PITA to re-prime. In 9mm, where brass is plentiful, easy to find and cheap, I would simply not waste my time with S&B brass, but your mileage may vary.
Powder: I've tried more than a half-dozen in 9mm and I have settled on Hodgdon Universal. (they call it "Universal Clays" on the package)
For me, it's accurate, meters very well, is economical, easy to find, available in 8 lb jugs, can be used in many different places and published load data is widely available. Universal works so well for me in 9mm that I have quit trying other powders in 9mm. And I have like 15 different handgun powders on hand, so it should be obvious that I love to experiment.
W231, Power Pistol and a slew of others are all fine powders for 9mm, but my vote is Universal.
Attention Brass rats and other reloaders: I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.