If he's old enough to have researched it, yes, then he wants a pellet gun. I didn't know what I wanted and Dad knew best. The pellet gun was so accurate one of my clear childhood memories was a friend challenging me to shoot the end of a twig off at a distance and I got it. He responded "WOW - I WANT TO TRY IT!" Great fun...
The kid wants a BB gun, get him a BB gun.