Is he trained to stop or sit on a whistle ? I am currently working on my dog with similar issues sort of, I keep him staked but before I did that if he broke I could almost always stop him immediately with a whistle but I know that is a lot to ask when you have a call in one hand and a gun in the other sometime you don't think fast enough to grab the whistle. Hunting with friends and working your dog on a lead is a good option I did that with my first retriever and he caught on really quick. Now I do a big correction with the ecollar if my new one braks or attempts it. Trying to replicate it in training is always better than the field. It took me a while to get mine to do it in training but eventually he did it then you can start from there good luck

