I'm wistfully remembering a time when I put marbles in my Hidden Shot and did some massive damage to my room. Not all marbles fit properly into the barrel, so it was guess and check for a while until I had a good pile of the correct size.
In retrospect, aiming at the things on my wall was not the best idea. I have a lot of things under glass on that wall, and unfortunately a few of them aren't under glass any more. In addition to being hazardous to life and limb, marbles shot from a nerf weapon make a god-awful noise when they hit something hard. "Clack! Tonk! Ping!"
The worst aspect of my near-lethal ammo was that if it was the right size, it wouldn't fire because it was lodged too tight in the barrel and the plunger on the hidden shot couldn't provide enough pressure. I ended up put the gun under water and letting the chamber fill up in order to get something with substance to push the marble out. Even worse, the marbles seemed to accelerate to dangerous speeds with these treatment. I'm just glad I still have a mirror in my bathroom.