A few months ago I bought three boxes of Win PDX1 9mm 124 +P. I loaded my Sigma 9VE and on the first round I racked the slide did not go to battery. I thought WTH and found my slide stuck. I had to get my rubber mallet, go out in my back yard and tapped in the slide til I can pull it open. I looked at the cartridge and noticed something unusual. I went through the boxes and found 4 more like it. It's a good thing it was the first round that stopped me because I don't know what would've happened if I fired it halfway in the mag. KABOOM! I suppose.
I learned my lesson about trusting factory loads. Each and every round are hand tested in the chamber since then.
In this pic is the 5 bad next to 2 good. Looks like the wrong bullets put in the 9mm cases.