We're with Chrismahon on this one......although ours is not wall-mounted but mounted on a large floor paving slab. I don't like killing anything - so it has to be done quickly, quietly, out of sight of it's 'family', without pain and with whatever dignity I can give........... We have our own home-made cone that we have used for years............. It can be hund up after the deed and for the bleeding.
For larger birds - we also despatch many, many turkeys and geese at Christmas - it is the iron bar (forget the paltry wooden broomstick) - with me standing on the bar and my 6ft+ oH doing the pulling. I hate it! but it is the quick, most efficient and painless way that I can do at the moment. I am currently looking into stun guns from the USA at the moment (although I do have an air rifle for rat-shooting!)
It comes down to whatever you fell is the most suitable for you, your birds, and your environment but will only be found with experience,