With a kid that young, do him a big favor: Teach him to shoot a rifle, with open sights( or that peep sight) by getting him a single shot bolt action .22 rifle. with open sights. He can shoot a lot of ammo, at low cost, and learn marksmanship fundamentals.
I practiced with my .22 for years before getting serious about any center fire rifle, much less a mler. But, I learned sight alignment, stance, mount, breath control, squeezing a lousy trigger, and follow through, all using that .22 rifle. I still have it. I can still shot it pretty well, even after years of just leaving it in the closet when I take newer .22 rifles out to the range.
I don't believe there is any "quick way" to teach anyone to be a good shot. Oh, I can get them hitting targets all right, but so much of shooting is "muscle memory", that you have to spend the time shooting lots.
When I began shooting MLers, I stopped shooting all my rifles and handguns, while I learned to shoot my ML rifle. It was 2 years before I shot any kind of rifle other than my MLer, again.
The hardest thing to teach another shooter, and the hardest part of shooting is learning to focus on that front sight on your rifle, or handgun. Sight alignment comes next, but is infinitely easier to do if you are shooting a peep sight that is mounted no more than 5" from your pupil. You simply look through a peep sight and focus on the front sight. Now, where you place the top of the front sight, be it a post, bead, upside down wedge=whatever--- is really the choice of any given shooter.
No two shooters hold the front sight the same on a given target. Sometimes, you find that you can shoot good scores with someone else's gun, without changing the sights, but its an event noteworthy because it happens so rarely. I was showing a friend my shotgun slug barrel, one day, and fired the first shot through the x in the X-ring, and then fired the next two shots with the three holes overlapping. We were standing off-hand at 50 yds. I then gave him the gun, and loaded the last 2 rds. from the box into the gun and had him shoot the 2 shots. His two shots were just a bit high with one at 10 o'clock and the second at 2 o'clock each about 1 inch off from the first hole. The entire group of five shots could be touched with a silver dollar, and and even at the outside measurements, it did not go 3 inches.
He had not shot a shotgun shooting slugs in years, nor had he ever shot a gun with a recoil pad on it, or that fit him. He was delighted that his two shot landed so close to my small group. I have relieved the throat in my slug barrel, which prevents damage to the soft slugs as they leave the chamber, and casing. I also have the muzzle ported, to keep the recoil from making the muzzle climb. That was an experience for him to see and feel.
My only thought was how he had to have held up more of the front sight than I do, to have had those 2 shots hit so much higher and away from my group!
My Identical Twin Brother and I can shoot each other's guns and open sights fairly well, without changes. But that was not the case with our father's guns. He could not shoot ours either, without change the sight adjustments.
So, I personally believe you are doing a lot of wishing and hoping if you think your son will shoot those sights the same as you do. I don't mean that either of you will miss the paper target. But, its more likely that even with a scope sight, your POI will differ from his. That has been my experience both personally, and as a shooting coach with other shooters.
