I've had a Leupold 6x42 with heavy duplex reticle on my .375 H&H for over 20 years now with no problem - the current equivalent model can be seen at
http://www.leupold.com/hunting-shoot...s/fx-3-6x42mm/
This has been on a couple of African safaris and has never given me the least bit of difficulty; since you mentioned you were " . . . looking for which one tends to be a little more rugged . . . " this may be a good data point.