I'd have to agree, 3-1/2 is pretty young- about the best you can do is hold a .22 rifle & let her pull the trigger (& that might not be a good idea, it may give her the idea that it is safe to shoot a gun that she may come in contact with at a later time).
I think I might have told this here once before, but for those who missed it:
We adopted our daughter at 6 years of age, after she had spent her entire life constantly suffering various forms of abuse & neglect. The professionals involved with her case told us that she was severely delayed socially, emotionally and academically. They told us not to expect much from her, that we had better be prepared to parent a very young child for the rest of our lives. They went on to tell us that she had no "cause & effect" thinking, & most likely
never would. Yes, she had a lot of problems, but they were environmental in nature. dd is 10 now, and those same professionals stand in silent awe when we take her to meetings and other functions. She is the most mature & responsible 10 year old that any of them have known.
I got dd her first rifle, a little youth sized Chipmonk when she turned 8. She already knew how serious I take handling firearms, so she went out of her way to memorize (and understand) the Basic Firearms Safety Rules. After that, I gave her about 15 minutes worth of instruction on grip, stance, sight picture and trigger control & we headed out back to the range. I demonstrated the loading/firing/unloading technique & set up a pepsi can 20-30 feet away. I stayed
very close by and gave her her first round of Aguila Super Colibri, a primer powered, powderless .22 round that is nearly silent (dd has an audio sensitivity problem). She carefully loaded, aimed, and fired. She missed the small target by a foot or more & I was disappointed for her (I guess someone had to be, lol). She took another round, loaded, aimed more carefully & set that can sailing!
She then proceded to pelt that poor can 1/2 way across the barnyard, jacking shells in&out of the little single shot rifle like an old pro
She got 9 hits out of her first 10 shots (including that first miss). She was soooooo jazzed, & wanted to carry the rifle back to the house. She did so with extreme care & responsibility. 8 years old seemed like the perfect time for her.
Teaching a child to shoot using a firearm that is scaled to fit them is a big plus. Picture your adult self, never having fired a shot in your life, trying to learn to shoot with a 8 foot long, 22 pound rifle with a length of pull equal to 1-1/2 times your arm's legth.
dd's first can:
http://tinypic.com/a0ucfk.jpg