Most of the Feist I've seen are a mix of Jack Russel and/or Fox Terrier and hound. I've got one now, he is a Plummer Terrier, mix of Jack Russel, Beagle and Bull Terrier. Twenty pounds of solid muscle, with shorter legs than yours, he is nose dominant, a born tracker.
Hard to tell sometimes which traits are going to be dominant, even in Dogs that look almost identical. His daughter looks almost identical to him, but uses all of her senses and has the habit of sticking her nose into any nook, crack, crevice or hole she can find. If she can fit, she is down that hole jiffy quick.
I've got a buddy now who has a Feist, his has wire hair, but is very like your dog in most other aspects. His Dog seems to cover twice as much territory as the other dogs do and seems to be everywhere at once. A really good Hare or Rabbit dog. Also good at flushing Pheasant. I watched him kill a Doe one day. She thought she would hide and wait until everybody passed by, he happened on her and had her neck opened up in nothing flat. I was surprised a Dog that small (under 30 pounds) could kill a 40 pound Deer that quick.
It's good your dog loops and come back to check in, I'd encourage it. Many Terriers can be hard to recover (get to come back).