If he's really just being bratty, he's trying to get a reaction out of you, so when he turns into you and you get all frustrated and whip him back on the circle, you've showed him you're not in control of your emotions so you cant be in control of his emotions or him in general. So when he turns into you, bring him in, pet him, back him back out and politely ask him to start circling again. And EVERY TIME he turns into you, do that. I had a horse that did this exact same thing. And it takes a lot of patience to not get frustrated when things like this happen. But it will just blow his mind when you dont get frustrated at him. It might take a few days, or it might take a few weeks for him to get over this behaviour, but you need to stay patient to show him you ARE in control.
It's hard for me to tell you what to do about the bucking w/o seeing it, but you can either ignore it, or when he gets high on adrenaline like that, help him use it up faster by PATIENTLY telling him to go faster and not letting him stop until you see the change in behaviour: lower head, calmer, slower. But I wouldn't do this right away. The bucking should go away after you start doing what I said above, you show him you're paying attention to his feelings and he probably will stop.
Ponies are very smart, you have to out smart them. If you have a round pen I would start there. Get the pony going around until the pony is working nicely in both directions. This might take a week or two. Once he is working well off the line attach the line and continue your routine. As far as the bucking, if it is while you are lounging him just keep him moving until he stops. He will eventulaly stop. Don't let him out smart you. If it is while you are ridding him, keep his feet moving forward. You might have to work with him twice a day until he stops. I have had some ponies where we had to work with them twice a day for a while to inforce what we were doing. Mainly you have to work with a pony daily and don't let them out smart you.
I wish I had read this initially. I hope you have been able to overcome your situation but in the off chance you are still contending with this situation I can offer you some valuable help. Visit www.christapetrillotraining.com. There you will find a "Just Ask Christa" page. Fill out the form and she will reply back to you with advice. She uses the John Lyons techniques in her training and is John Lyons Certified...John Lyons has been around for decades. Why? Because his techniques really do work! Round penning is often a valuable way to correct behavioral issues such as you have described. I respectfully disagree with the first post here because by bringing your POA to you, you have given it a release or reward You have actually enforced his behavior. Turning into you could be agreesive behavior- you probably know that...not something you want to enforce or reward. Turning in is oklay if you have initiated it or asked for it... but generally not something you want to do until you have established complete control and respect- which may take a bit. John Lyon's Round Penning Technique is a specific way of round penning... correctly... for optimum results. Christa can tell you how to accomplish it or you can read it in one of his books... I do agree with controlling your emotions... Christa never allows bucking because round penning is working. A horse should never buck when working. They have a turn out for that. So what she does is turns them to the outside and makes them go the other direction or speed them up. Do not leave the status quo as is. By disengaging the hind end and making them turn you have made them change direction and actually have done what a dominant horse often does in the pasture when chasing another less dominant horse- you have controlled their movement. Control is the key word. They would rather do it right than have to make a bunch of directional changes- they catch on pretty well eventually. Ponies are smart- they can connect the dots pretty well. :-) Best of luck to you...
It's hard for me to tell you what to do about the bucking w/o seeing it, but you can either ignore it, or when he gets high on adrenaline like that, help him use it up faster by PATIENTLY telling him to go faster and not letting him stop until you see the change in behaviour: lower head, calmer, slower. But I wouldn't do this right away. The bucking should go away after you start doing what I said above, you show him you're paying attention to his feelings and he probably will stop.
Hope that helps!