Shooting .22 Long rifle in your gun should be just fine .
The bore diameter of the barrel is slightly smaller than the bullet and trying to push the bullet into the bore from the front will not work.
Some cylinder guns in .22 caliber came with both a .22 LR and a .22 magnum cylinder that would interchange in the gun. I have no idea whether yours would have been such a gun ,but strongly suspect not, as generaly only Ruger or Colt made these. The .22 LR round should fit without being sloppy in the chamber - also the .22 Magnum cylinders were typically stamped as such. If there are no markings on the cylinder and the .22 LR cartridges slide in without being sloppy in the chamber, you should be good to go.