You can also get pleats, in the case of stock systems as they are basically all the same shape [contour-wise] and heads/skulls are not all the same shape obviously, therefore as you might imagine , the perimeter of a stock can sometimes slightly `bunch-up`or have pleats form, simply because it is not a snug fit to the exact contour of YOUR particular head .... some people find they get a really nice fit and that`s great for them, but others will find pleats forming --especially up around the crown where the growing hair would have/used to form a swirl.....that`s about the point/area where the `sharpest`change of skull shape occurs..it`s perfectly understandable ..... THE best-fit for you, is normally by making a template of YOUR individual head-shape/contour and you`ll have a nice fit, when your customs arrives ....the stocks are fine and suit many wearers very well...indeed the materials and quality are exactly the same as custom-made...just that some bunching-up /pleating can occur ---it feels worse to you when you feel it with your fingers but in reality is actually quite small ..a minor annoyance [if it occurs] which you will not have once your custom-made system is delivered... Paul.