The 30mm tube will not bend as easily as the 1" (though it may dent just as easily). Probably an academic point.
Evidence of this can be seen in the design of bicycle frames. Notice the diameter of the oversized tubing used on high-end aluminum manufacturers. The larger diameter is reported to increase rigidity. Same with aluminum arrow manufacturers. When the wall thickness is the same(designated by the last 2 digits in the size), the largest diameter will always have a heavier spine than the smaller diameter arrow. The first 2 digits of the size denotes diameter. For instance, "
2117".
30mm tubes allow more room for movement of the internal optics, so you may have more range of adjustment....
This is more true of american-based manufacturers. They use the same reticle tube diameter in the 1" and 30mm designs. Here the gain is added elevation & windage adjustment. Most European manufactureres use a larger diameter reticle-tube. While the elevation & windage adjustment is decreased, the area of light that's transmitted is increased.
To see the difference, just look down the end of a small pipe into the distance. Then do the same with a pipe of larger diameter. The larger diameter pipe is allowing a greater amount of light and image to be gathered by the eye. This would simulate the larger diameter internal reticle tube used on European optics. While for many years people have claimed there is no difference between the 1" & 30mm in lowlight, it's only when the same diameter reticle tube is used in both. When you increase the diameter of the internal reticle tube, the transmission is also increased.
Side by side, the difference between my Leupold MK4 and Swarovskis are very noticable. And both have 30mm maintubes. When I shine a light inside the objective-end of each I can see the difference in tube size is much different. While the MK4 has alot of space surrounding it for adjustment, the Swarovski's is much larger.
Basically, there are 2 types of 30mm scopes. Those designed for 'optimum' adjustment, and those designed for 'optimum' transmission. Though it's very rare that this is mentioned. Most only refer to the american style and say there is no difference between the transmission of the 1" & 30mm.
