Your dove shoots are likely over by now, but there's still time to get in some meaningful field training before the serious hunting starts.
Last year, a friend's spaniel consistently hunted short for fallen birds on retrieves. I had run into the same problem myself years ago.
Generally, the dogs could be handled to go deep enough to find the bird, but we were not happy handling our dogs on retrieves we felt should have been marked accurately and found on their first effort.
To encourage pup to punch out farther for retrieves, start in a large field with short grass that will allow retrieves of a decent distance. Hup pup where you wish, walk a good 20 yards away from him and toss a retrieving dummy a good distance away from pup, but don't be excessive.
Return to pup, and since he watched you toss the dummy, call his name (the voice command to retrieve) to send him for the tossed dummy. He should race directly toward the dummy, and hopefully the extra distance will go unnoticed and he will make the retrieve immediately.
As long as pup makes the retrieve, give him two more at the same distance. Praise pup if those go well.
Take a short break and move to a different part of the field and do the same thing. If those are successful praise pup and give him another break.
Now use a dummy launcher fired with .22 blanks to provide pup with additional retrieves of roughly the same distance as before. Three retrieves are enough, so take a break and have some fun time with pup.
Next session should be done in higher grass, but this time have a helper walk away from pup while you remain with him. Have the helper toss a dummy about the same distance as your first session. If successful, have your assistant move and toss the dummy to another area.
You give pup the command to retrieve (his name) and praise him when he returns with the dummy.
Try puppy training a few times a week, and if possible, move to different locations for pup's retrieving drills. Toss the dummy by hand and with a dummy launcher to provide pup with different experiences.
Now review your "back" drill with pup so you have a way to send him deeper on a retrieve if he hunts short.
It is helpful if you have a worn path on one of your training fields for this drill. Start relatively far away from your normal starting point and hup pup at your side, facing back toward your vehicle or normal starting area.
You are also facing the starting area and pup is on your left side so you can heel pup back toward the starting area when you are ready.
Take a dead pigeon from your puppy training vest and make sure pup sees it before tossing it about eight to 10 feet behind pup so it lands on the worn path in the field. Do not let pup break and retrieve the bird.
Instead, heel pup back toward the car or starting area, and walk at least 25 yards before stopping with pup, and turning yourself around to face the tossed pigeon.
Pup is facing you while you face pup and the pigeon. Command "Back" at the same time you quickly raise your right hand and arm and point toward the dead pigeon.
Since this is a review, pup should spin and quickly race back over the beaten path until he finds the pigeon, then quickly retrieve the bird to hand. Praise pup and give him a break.
Repeat that drill twice, adding 10-15 yards to each retrieve. Praise pup each time he succeeds.
This drill should be done several times a week and should be lengthened to no more than 100 yards. When the drill is done over time the distance should be alternated from about 40 yards to 100 yards.
There are a couple of goals for this drill one, so pup learns that all retrieves are not the same distance; and two, that some retrieves can be quite far so he keeps on plugging until his nose picks up the scent of the fallen bird.
The preceding drill was originally used to teach pup to "go back" and retrieve a bird when the voice command "back" was used in conjunction with the hand and arm signal.
If you have several friends with trained spaniels you can do another drill that will help the dogs to judge different distances and at the same time help develop and solidify their steadiness. Some of the retrieves should be fairly far.
Sit two or three dogs five feet apart facing downfield with their owners standing behind them if the dogs are pretty steady. The field should have short to moderate cover. If some dogs are likely to break before being sent to retrieve, their owners should stand about 10 feet in front of the dogs.
Using the dummy launcher (put some pheasant scent on the dummy), a training partner without a dog in the drill will stand about 10 feet in front of the dogs so that he can shoot the dummy downfield using the launcher, while also seeing the dogs before the dummy is launched.
Each dog is facing downfield and given the "hup" command by its owner. The dog's attention is drawn to the person with the dummy launcher and when he and the pups are ready, the dummy will be fired/launched downfield. All dogs will no doubt be focusing on the dummy, and hopefully all will be steady.
Immediately after the dummy lands a pre-determined owner will call out his dog's name, which is the signal to retrieve. The named dog should race for the dummy while the other dog or two remain seated, thus steady.
The retrieving dog makes the retrieve and returns it to his owner, while the waiting dogs continue to remain seated.
Repeat the drill with dummies being launched to different areas of the field at different distances. Mix which dog retrieves to both rest dogs and so the dogs do not know which dog will be sent.
This is excellent puppy training; to learn to judge distances while reinforcing steadiness.
I like to have dogs learn to judge distances via practice and do not especially like to get involved teaching dogs to take a line, or hand signal for distant retrieves. For short to moderate distances hand signals suit me, but not for long retrieves.
The problem I have with giving long lines and expecting spaniels to run long straight lines is that running long distances in straight lines is against a springer spaniel's nature. Springers naturally hunt via quartering and searching for scent; long, straight lines go against their DNA, and I do not care to do that.
Have a great, safe hunting season, and take care of your four-footed best friend!