Ok, did some quick research. A tube with a larger diameter but the same wall thickness has a lower burst pressure. So if you were going to fill it with high pressure air or liquid a smaller diameter tube would be stronger. However a larger diameter tube would be stiffer for the same length, as in it would be harder to bend. This evident when looking at spine charts for arrows. With arrows of the same wall thickness the arrow with the larger diameter has the stiffer spine reaction.

I think either would probably dent just as easily especially with the sizes we are talking about. In order to make it more resistant to denting it would either have to be a stronger alloy or have a thicker wall.

Something to keep in mind though is normally when tubing diameter increases so does the wall thickness. So without knowing the exact specs of the tubing used for the scope it would be hard to say which would be stronger or not.

You would also have to deal with getting 30mm rings, which might be harder to find and more expensive to buy.

And I prefer AO adjustable scopes over side focus. With the side focus they are only accurate in one direction, so if you over shoot your focus point you have to turn it all the way back again. I don't believe this is true with the objective focus rings.

Paul