The extractor grooves in PPU cases are notoriously not cut deep enough and they won't fit between the sides of the inner lips of the shell head holder.
I've run into similar issues with RWS and Norma, but the thickness of the rim is usually the problem
I have a #2 RCBS shell head holder that I ground out that inner surface to clear the shallow extractor cuts and keep it set aside for just such situations.
I often have newbies wanting to learn the process of reloading. It's not surprising that they show up with sportered milsurps and components that aren't top of the line when it comes to quality.
I'm not going to knock PPU ammo or components. They're not my first choice though and have enabled me to get some rifles shooting that I never thought was going to happen, without a lot of tedious fiddly work on my part.
I very seldom have issues with RWS ammo or components.
The biggest problem I've come across over the last five or so years is the poor quality of the brass cases which are mostly dimensionally fine.
I don't believe ammunition manufacturers are overly interested in having their products reloaded. As long as they go bang, in a reasonably consistent, safe manner and eject after the first firing, they couldn't care less what happens after that