Well panzer 3s even with their barrel upgrade are only an improvement to penetration, and the churchill is known for its tough armor and for being a unit to soak up damage. Most likley would have been luck. I've seen times when bazooka shells bounced off the rear end of a king tiger.
Wait, I think that the panzer 3 with the 50mm might have the same or atleast similar penetration to the american bazooka. Maybe we could use that as a rough comparison?