Look at the Gap
Squirrel, if you hold your revolver up sideways to a bright light, you can see the gap between the cylinder and barrel. It typically may be on the order of about 0.002" wide; that's the diameter of a human hair. The larger the gap (cheaper, poorly constructed revolvers) the larger the amount of high-pressure gas which escapes during firing. This escaping gas, especially in magnum calibers, constitutes a safety hazard to human parts, fingers, and such, held closer to the firing gun than a foot or so away. Occasionally, misalignment between the chamber and barrel causes fine slivers of metal to be shaved off and spat out sideways.
It is because of this gap that revolvers cannot be effectively "silenced", using a more-correctly referred to term, "suppressed".