We arrived about 11 PM on a Saturday night, and a reservation was not necessary. I cannot speak about prime dinner hour, though.
No! No need for reservation:)
We were there a bit early, between 5 & 6pm, and we had no need of a reservation. They seated us very quickly. I think if you were to go later, a reservation would be a good idea.
Get quick answers from Stoney's Bar and Grill staff and past visitors.