Yesterday I went into the paddock with a crop (that's what we called them in Australia, I think they are called riding sticks in the US, a short whip), with it tucked up my jumper so he couldn't see it. I made him run around and move his back end around, and back up which I've taught him from voice command so I don't need to touch him which is asking for a bite!
I'd rather not give him the opportunity. Then as soon as he put his head up and ears back at me I whipped out the crop and gave him a sharp smack on his chest. He ran back about ten strides with his head bobbing about but ears still back, he didn't have a clue what had just happened! And he didn't like it at all. So I did this a couple times when he got nasty but didn't push it too much, then he was at the point where he was submissive and calm and following my feet. He's a very quick learner and really smart, so hopefully he'll realise he won't know whether he's going to get a smack or not and he'll calm down. I will try all of your ideas for sure though to mix it up a bit :) thank you! He'll probably get too smart for the whip soon anyway.
Affored - I agree with you 100%. I never hand feed him, but I pat him and he always manages to find a way of being naughty. Sometimes I go through a week or so of just giving him tough love, pushing past him and making him do what I want, not being nice at all. But it never lasts for long :( often because I feel sorry for him. I need to really try and make it a long-term thing, with the things that you mentioned.
Peppersgirl - I have tried using my elbow on him every time he bit me for months on end, unfortunately it made no difference. I don't know why! Thank you though
Inga - I have been meaning to put some mustard or something on my boot so that when he bites that he will get a nasty taste. I hadn't thought of thumb tacks in a jacket though, it sounds like it would probably work - for when he tries to nip me when I clean out his hooves too.
DRichmond - He seems to act the same with women and men - he bites my little sister as well as my dad and hoof trimmer who is a male, although he doesn't get away with much with the hoof trimmer. They never really put themselves in a position where he becomes aggressive though, so I'm not sure what would happen there. I probably should have said more about him under saddle - he's not dangerous but he will try to get away with anything he can. Has the occassional bucking hissy fit and tries to run out of the arena or not do something he doesn't want to do, I always feel as though I have better control of him when I'm on him for some reason though. Not that I constantly yank his mouth off or anything, I (hope) I'm always pretty light on the reins :) My dad actually said the other day I should try and just be really quiet and calm when his mouth comes at me to surprise him, I'll try it and see what happens, thanks