I would definitely determine that all the after market parts are all installed correctly and not loose or missing.
How is your recoil spring/guide rod assembly looking?
Limp wristing can always cause feeding issues. I had to learn to be more conscious of my grip due to some malfunctions with the VP9 caused by poor handling before I could relegate the grip back to my subconscious mechanics. With it happening once every few hundred rounds, it makes me wonder if you just have a bad purchase on the firearm from time to time.