to Poppy1356: I have been feeding Pistol sweet feed. I never realized that could be part of the issue. Apparently all that sugar is hyping him up a bit. Next trip to the feed bin I will be getting a low/no molasses feed/supplement. I probably don't work him as much as I should either. Every other day or two has been the norm except for the 15 minutes during feeding that I brush and groom him and stomp around to get him used to movements and noise, etc. A horse is only as good as its owner.
You'll cause a nuclear explosion feeding like that!
I feel for you again, because I use to feed and work my mare just like you're doing yours right now. Actually, I was WAY worse. She got 4 pounds of sweet feed a day, alfalfa hay, and got worked once every couple weeks.
You can take your horse off grain completely. As long as he has enough hay, you don't need grain. A ration balancer would provide vitamins and minerals, but your horse won't die without one.
If he has a hard time keeping weight without grain, I really like this stuff called Cool Calories 100. It's basically dry vegetable oil. 100% fat supplement. My mare gets two cups a day of Cool Calories and 3 pounds of super low sugar/carbohydrate, high fat feed.
I've done a TON of experimenting with feed because my mare has PSSM. I've tried every major feed brand, several lesser known ones, and every fat supplement I can find. Plus several ration balancers and vitamin/mineral supplements.
If you need any help with feed, shoot me a question. I can e-mail my nutritionist if I can't give you an answer!