Ten points to consider .
1, You can not fit a gun for a man who can not shoot [novice].
2, Some people will never be able to shoot well no matter what is done to the stock.
3, You can not fit a gun to a man who will not listen.
4, Physical problems ,as well as physique
biuld ,hight ,weight ,size of limbs/hands etc.
5, Physcalogical problems ,
6, The wrong gun.
7, You will need lessons.
8, Getting past ingrained habits /past incorrect coaching.
9, 50% of problems are related to stance and mount .
10,What can actualy be done to the gun in way of altering the stock .

This is part of some musings I am currently compiling for a future publication .Each of these points is explained and discussed .