Sticky extraction and case head expansion. Covered in my reloading manuals...
You are making the very common error of applying rifle loading procedures to handguns. Read your manuals again.
I will add that if you get sticky extraction from a bolt action rifle, you are way over pressure (over 65,000 psi?). If you are getting it in a handgun, those loads are flat out hazardous. In this case, the shooter in the OP was shooting the loads in a semi-auto pistol, so he had no way to determine what the extraction was like.
Case head expansion only applies to new cases, and only comes into play, again, at rifle pressures. If you are getting those indications in a pistol or revolver, you are WAY over pressure.
"Reading primers"? Don't even get me started!
When I first started re-loading I wrecked a brand new Model 19. I followed the data on the old (and foolishly high) Speer manual, all while watching carefully for "signs of pressure", as advised in the manual. By the time I noticed them, the forcing cone on my gun was split and the cylinder bulged.
There is no reliable, objective method to determine pressure for the typical handgun re-loader, and it chaps my --- to see the constant admonitions to "watch for pressure signs" in regard to pistols and revolvers. There are no indications until you are way over the line.
Get your data from a reliable source and adhere to it closely, including overall cartridge length. Get a chronograph, and if you are getting higher speeds than factory ammo, you are over pressure.