I normally prefer a double rifle for this application, since having an immediately available follow up shot can make all the difference.
The broadside heart/lung shot on a Tyrannosaur, while effective, does not incapacitate them quickly enough to prevent mayhem. The high shoulder/spine shot is effective, but can be difficult to visualize with the relatively unfamiliar saurian anatomy. Since the animal is normally facing you directly (or charging) you may not have this presentation anyway, unless you can surprise him feeding on a carcass. I do need to speak to Kevin about adding some anatomy diagrams to the next edition of The Perfect Shot.
Solid bullets are of course mandatory, preferably in 500 grain or larger size, with at least 2100fps at the muzzle. There is some debate on this subject, but I think 470NE would be the absolute minimum caliber here, and a 500NE or 577NE may provide the crucial extra inches (I'm talking about inches of wound penetration here, get your mind out of the gutter).
The generally accepted wisdom is to use the "broomstick method" to visualize the location of the (admittedly tiny) brain. In point of fact, the brain is roughly the size of a large avocado.
Since they tend to charge with the head held high, you may find yourself needing to shoot up at a very steep angle; the head is normally about 20 feet or so above ground level, roughly the height of a two story building. Just locate the gaping jaws filled with pointy teeth and aim high through the roof of the mouth, to break the broomstick.
It's worth mentioning that the tail sweep can be a devastating and unanticipated attack, and one not often encountered with other DG. Be prepared to drop quickly if he brings that big tail around.
You will also need to practice spinning quickly to acquire a moving target, in the event he is stalking you from behind (objects in the rearview mirror are larger than they appear).
Oh, and you may want to consider the wisdom of wearing your favorite CMS shirt; there is some evidence these shirts may actually provoke a charge.
One last thing: be aware that the males and females are known to hunt cooperatively during the breeding season.
Weidmannsheil!
