yeah, thats about the same size as the scimitar oryx..
Wrong again, gemsbok are 30% bigger, why are you talking about scimitar oryx in a conversation on gemsbok? It's like talking about key deer in a mule deer conversation.
the size of a large mule deer,
Wrong again, a large gemsbok is twice the size of a large mule deer, and again, much tougher than anything in the deer family.
or a female elk.. and gee, so many people kill those with .30-30s, 243s, even knew someone in arizona who would only hunt them with a 44 mag marlin with people cleanly killing them at about 400 yards with 6.5x55
theres absolutely nothing to back up your statement of 6.5x55 being inadequate for a 500 pound ungulate
I'll go with the advice of my guide with 25 year's experience over an armchair internet expert who probably never heard of an oryx before this thread. You might master sentence capitalization and punctuation before you opine on appropriate gemsbok cartridges.