How to tell if the gun fits
Most modern day manufactures have got this all sorted and most off-the-peg guns are intended to suit and fit the average shooter with an average build and stature. In simple terms, a taller person needs a gun with a longer stock, while a person of smaller stature needs a shorter one.
Comb height can be easily seen by mounting your gun at a mirror to see the position of the eye in relation to the rib and the view. If the eye is too high, the gun will shoot high, whereas if the eye is too low then the non-shooting eye will take over and the gun will not shoot where it’s intended or the head will be lifted. Then, of course, the relationship of the eye to the gun is completely destroyed. Here’s an image showing the shooter’s view and what you should see.