My rifle was an E.R. Shaw Mark VII, ordered specifically for this hunt about two years ago. It's chambered in the .416 Remington caliber.
Shaw makes rifles to order. Their guns are built on brand new Savage long actions with the Accu-Trigger feature. The buyer can specify his preference of calibers, barrel types, contours, fluting, etc. as well as material (blued of stainless) and stock (synthetic, walnut, or laminated). Shaw doesn't mount open sights; I had the set of Weaver sights added by my gunsmith. No one in his right mind would have a dangerous game rifle without a set of open sights!
Aimpoint makes a very tough, compact, and effective red dot sight, and I chose their Micro H1 for this rifle. Throughout the practice sessions and the hunt, this sight was totally unaffected by the .416's vicious recoil, and held its zero in transit despite the best efforts of the airline baggage-handling gorillas in throwing my gun case around.
Ammunition in .416 Remington is made by several companies. I used Hornady's "Dangerous Game" series with a 400-grain solid bullet. This generates about 5100 foot-pounds of muzzle energy, and when you pull the trigger you really feel you have accomplished something. It performed perfectly on this hunt. At left is a picture of one of the bullets recovered from my elephant: it was the "insurance" shot that I fired into the back of his neck. After moving though several feet of elephant muscle and bone, it came to lodge in the tongue, where the skinners recovered it. It was totally un-deformed and had retained 100% of its original weight. That's exactly what you want in a big game bullet. Best of all, this superb Hornday ammunition sells for much less than other brands.