Thanks for the input. To be clear, the revolver is the same "gun" in the movie, it gets knocked out of the bad guy's hand and into Don Knotts'. But I agree with your assessment that they're different props, which is weird. The gun is never fired in the film. It almost looks like live rounds in the chamber when Don Knotts is holding it, but I'm no expert. It's at least supposed to look like live rounds, I guess.
Looking at it closer in this pic and comparing the 36 to the Detective Special, I'm not so sure it's either at this point.
If you look closely, there appears to be a small arch in the frame between the hammer and the grip. Can you make it out?
Thanks again,
Dan