I have a Mini gelding who is coming up on 2 years old. He is VERY nippy, and despite my constant behavioral corrections, remains nippy. When he nips, I grab the long hair on the side of his head (between the muzzle and cheek) and twist (he's quite fuzzy right now from his winter coat so the hair is easily grabbed and twisted). The woman who I board with advised me to do this, assuring that it does not harm the horse and corrects nipping/biting. I have also tried immediately backing him, when he nips while leading. However, Koda just does not seem to respond to corrections. I go as far as I can with punishments but avoid anything like physical abuse (of course).
He is also constantly pestering his companion, a 30 year old Shetland named Hammer, and nips at his hindquarters and tail all the time (though it may just be around feeding time that they start this nipping war). Poor old Hammer has had most of his tail ripped out by Koda, the little twerp. I'm pretty embarrassed that he's done that to Hammer, as Hammer's owner is the manager of the place I board and my farrier.
Please advise if you have experience with a hardheaded Miniature who just does not respond to corrections.
Years ago, I had another Miniature, who was also nippy and reared when he was young, but he was a gentleman by age 4. So, I'm hoping the same happens with Koda, but I'm getting tired of the constant battle of him nipping vs. me correcting. It is endless. I'm probably doing something wrong, so please help me be a better Mini owner!
Edited to add: He was gelded approximately 10 months ago.
ETA2: Round penning is not an option, because where I board, they took the round pen down to move it and have not put it back up yet, and, it's a very small diameter circle that I feel would stress his joints (they need way more panels).