For the purposes of some of the things you're asking- in a sense, yes, it could be useful to even have a toy gun- if you're talking about drawing it, holding it, carrying it. Actually firing feels very different- without the ejected casings, recoil power, breathing control, smoke, loud noise, it's not all that similar, like comparing Tee-ball to a baseball actually pitched at you. I have a fairly good quality Gamo air rifle, and while it superficially feels like a rifle, there's certain characteristics that it doesn't replicate, and it even adds its own- like ricocheting projectiles that come right back into my face if they hit something too round or even too soft. It can break a hard bottle at 20 meters, put a pellet about 1/2 the way into a thick phone book, but I've had pellets rebound off of rubber balls, plastic flower pots and come straight back at me- sounds like large bee whizzing past.