Safety first.
If the cylinder's chamber diameters are within a few thousandths of an inch of barrel bore diameter should be o.k. to shoot.
I have shot heavy bullets in quality guns, like a Uberti, Ruger or 2nd Generation Colt with no problem.
In some of the older and/or low end guns it would be better, especially with brass frame guns, to use round balls and moderate powder charges to delay loosening up the gun over time.
If you remain unsure or encounter a problem with the cylinder vs. bore size then pull the bullets or remove nipples and tap bullets out with a non-sparking rod after shaking out the powder. Deactivate any remaining powder with water or liquid soap.