There were two gunsmiths named Priest working in Cleveland OH. Joseph Priest and Josiah Priest. Both had moved to Detroit MI by 1850: some feel they might have been father and son, though no records exist for either one past 1857, so J. Priest could be one and the same person.
The rifle is marked with the words Grafton St so while the rifle could have been made in Grafton OH (about 40 miles from the original city of Cleveland) it is likely there was a Grafton Street which no longer exists today, or was re-named at some point.
There were not many gunsmiths in Cleveland OH at any time during the 1800's.
You rifle is a good quality picket rifle likely from the 1840's. If it has target sights or at one time had them it would be a target rifle. If not it would have been a hunting rifle. Not all picket rifles were used to target shoot, as many used the picket bullet because it was heavier, would shoot flatter and had more killing power than a round ball.
Nice rifle, enjoy it!