Yeah, if I recall, Mythbusters just used an ordinary rifle, like the
kind you might use to hunt deer. I'm not sure that the results would be
significantly different since in both cases there's nothing on either
bullet to keep it from tumbling in freefall, and therefore reaching a
low terminal velocity.
Still, I wouldn't want to be standing under anything that's metal,
falling and headed directly for my fragile head.
We had a large park two or three blocks away from my house when I was a
kid. One end of the park was a playground and the other end had an oval
running track on it. Most of the time there was never anyone in that
park. A friend of mine, Mike Mosquin, wanted to show me how powerful
his new fiberglass bow was, so he laid on his back in his yard, held
back the arrow with his fingers and pulled the bowstring tight by
pushing on the bow with his feet. He launched that arrow toward the
park. We walked to the park and found the arrow stuck in the grass
inside the oval track. That stuck me as a very dangerous thing to do
since neither of us could see who, if anyone, was in the park. But,
being all of 13 or 14 years old, we did it anyway. Luckily, no one got
hurt. Still, I couldn't help but wonder if that arrow would have had
the same penetrating force at the end of it's trajectory than near the
beginning of it's trajectory. I still don't know for sure. The arrow
was stuck in the ground, but (IIRC) it wasn't stuck in as deep as it
would if it were shot into the ground from a closer distance.