I don't have kids, but can reflect on my experience.
We played war and toy guns ALL the time. We used anything as a pretend gun....an actual toy gun, a broken super-soaker, a hockey stick...heck, wrapping paper tubes became bazookas! We ran around the yard fake-shooting, fake-dying, etc.
I stepped up to a "toy" crossbow that shot little suction cup darts. I knew, my parents made it clear, that that thing could do some damage if it hit you in the eye, and if I was caught aiming at my brothers, it would be gone and never come back. That didn't stop me from shooting it at the TV! (Back when we had CRTs with their thick glass that could handle it, and not flat-screens).
Then I upgraded to BB gun. That was serious business! It could break the skin!
It could take out an eye. It could kill...things. And you're darn sure I never aimed that thing at the TV. I treated it as a real gun for all practical purposes, except that I was allowed to shoot it outside unsupervised.
Then at age 12 came the .22. And essentially to me, it was a super lethal killing machine and I treated it with the utmost respect. Which is how any kid should view ANY gun. Of course, I still played with nerf guns, up to and including college. But by that point, age 12, I had the hunter safety course, and with a stepped, "tier" system, if the difference between a toy and the real deal isn't plain as day, something is wrong with either the kid or the parents.