Collar / Harness question

Actually you should try giving a head collar a try. I use one on my boy, he is almost 4 months and probably about 40lbs. In using a head collar you have control of where they go. My pup used to pull non stop, so I got the head collar. He doesn't pull anymore and walks with me. The head collar is designed to put pressure on the bridge of the nose and back of the head. When they pull they feel pressure which makes them not want to pull. If you have control of his head you control were his feet go. Its the same method for horses you control there head and not there neck other wise they would mow you down. With the head collar he can still pant, eat, drink, bark, etc. He would also have less strength to pull you, it's easier to pull you with their neck and chest. Sure he might make a big fuss over it being on his head but they get used to it and it really does work. It's worth a shot. I'm pleased with my results with it.

It sounds like the Colt is a strong and energetic dog that needs a secure collar or harness to keep him safe and under control while out and about. While a martingale collar can be helpful for some dogs, it may not be the best option for a Colt if he pulls hard.

A harness can be a good alternative for dogs that pull on a leash because it distributes pressure evenly across the dog's chest rather than pulling on the neck. However, not all harnesses are the same, and some may give your puppy more pulling power. Look for a harness with a front attachment point, as this will help to curb your dog's behavior by directing him to the side when he pulls.

Another option to consider is a no-pull harness that has leash attachments on the front and back, such as the Freedom No-Pull Harness. This type of harness provides better control and helps prevent pulling without putting excessive pressure on the colt's neck.

It is also important to continue to work on obedience training and leash training, as this will help improve the dog's behavior and reduce the number of pulls over time. Consistency and patience are key in training a strong dog like Colt, and it may take some time before you start to see progress.
I can also suggest considering a smart dog bark control collar. But only if you don't mind such collars.

Finally, if you are concerned about Colt's behavior around other dogs, it may be worth consulting a professional dog trainer or behaviorist who can work with you and Colt to address any aggression or reactivity issues he may be having.