The claim is often made here that if only Leupold could put the FXII optics into a longer tube, then the 4x33 would be a great scope. The obverse proposition (and likely intended meaning of the observation) being, of course, that the FXII is somehow defective. I used to believe this, somewhat. No more.
The claim that the FXII is too short is often coupled with the statement that such a short scope could never be mounted on a magnum length action, thus meaning that the 4x33 is not suitable to calibers such as 375 H&H.
That is wrong. Here is a picture of one of my FXII 4x33's resting in Burris steel weaver rings in steel Warne bases on my Winchester Model 70 375 H&H "Super Express." (It's scope switching day at my place so I've got a few laying about loose). Now, I chose these bases and rings because they offer not only strength but also place the rings closer together than other offerings. But, even so, there is enough room on the supposedly "short" FXII tube to mount the scope the way I like it: as forward as eye relief will allow.
Here's the pic:
And here is a side by side comparison of the FXII 4x33 and the famous "long tube" M8 4x28:
The 4x28 does indeed have a long tube, and for rifles such as the Ruger #1 it remains my top choice in 4x scopes because of the constraints imposed by the Ruger mounting system; e.g., without higher extension rings, or removing the rib and installing weaver bases, it is not possible to move the mounts forward or back to accomodate a short tube scope. That said, however, I no longer think there are any flies on the 4x33 when it comes to mounting, even on "long" actions.
Caveat: I no longer own a CZ 550 Magnum action so I couldn't do a test to see if the 4x33 would fit there. That might be an action too long, particularly given that the rear ring spacing is not changeable and there is little latitude with the front ring as well.