While you are on the site, in your browser find and click "Add to Home Screen" A CGN beaver app icon will then be created to your phone that is directly link to the site.
Note: This feature may not be available in some browsers.
The 'term' magnum is almost meaningless in modern shotguns. Chamber length is pretty much all you need to concern yourself with. A 3.5" (or 3" or 2-3/4") chamber can shoot everything that length and shorter.
As another note: some, not all, autoloading shotguns with the 3.5" chamber will not function reliably with 2 3/4" shells. From what I have read and been told there may not be enough energy to cycle the action.