To be fair, no method is infallible. 90% of animal suffering at harvest is fear or squeamishness on the part of the dispatcher, but the other 10% is human error. So commit, but accept that you are not perfect, you will sometimes get it wrong, and there is a learning curve.
You will make mistakes.
So do the people who harvest meat that is for sale in stores. There is no magic there, they are still humans who sometimes slip.
The only way to never cause an animal suffering for sure is to probably die...I do not say this lightly or facetiously. Even vegans tend to eat grain harvested by machine and, trust me, that is NEVER bloodless. Life feeds on life.
Ultimately I comfort myself for any errors by remembering that the fox, raccoon, or wolf makes no effort at all to prevent suffering in their meals. That we care makes us human. If it gets easy to kill, something is wrong.
There is a learning curve. If you are new to this, be kind to yourself. Recognize that trying is enough, and you will get better. I think this is what is causing some of the friction here, you are seeking a perfect way and it's not a thing--life and death are inherently messy.
I believe it is worth learning how to do this well, but I also respect those who feel that they cannot do it well, either due to temperament or physical capability, or circumstance. It is not that you harvest your own meat that matters to me. It is that you recognize that things must die to feed you and you are willing to own that and take responsibility for it however you are able. Maybe you only buy local, or you avoid animal products, or you develop a relationship with your local rancher...
Anything but say that someone who kills an animal they have carefully raised is a monster, while casually eating a cheeseburger from McDonald's. That brand of hypocrisy is hard to stomach, for me.
This is the type of stunner I use.
Bunny Rancher Ballista Bolt Gun
Honestly, it's a more disturbing looking death than cervical dislocation in my opinion. Rabbits kick more violently after a bolt to the brain than a broken neck, it is possible to mess up the placement, and I honestly prefer to do the cervical dislocation method, on any animal that I can physically manage. However a 13lb adult doe is too strong and large for my 5'6" frame to accurately handle.