It's not just the fit, or the expense, or the "shoot-ability" or lack thereof regarding a double rifle...... for a hunter going to Africa, a bolt rifle is a more effective weapon than a double! Don't get me wrong, I love double rifles, and have had 12-15 of them over time. They're nostalgic, powerful-looking, and downright cool! But we tend to confuse our role as hunter versus PH.
A double rifle provides 2 reliable shots with only the move of a finger from one trigger to another. They're shorter and can be handier than a longer bolt rifle, and in a large caliber in the hands of a PH, they can provide the stopping power needed when things get out of control on a hunt, protecting the client and the rest of the hunting party. At the short ranges used, a double provides the adequate "minute of Cape Buffalo" accuracy needed at short range.
The hunting client, however, has different responsibilities....to provide an accurate killing shot on an animal at the range encountered. To accomplish this, a scoped bolt rifle is the ticket. At the ranges generally encountered on a hunt, there's no need for 2 ultra-fast and reliable shots, so a bolt is fine. Accuracy becomes more critical as distance increases, so an accurate rifle and a scope aid in precise shot placement.
Double rifles may look powerful, but being break-open actions, they're limited in chamber pressure. To make up for that, the more powerful versions use very heavy bullet weights, which are a detriment to both range and trajectory.
Double rifles are designed to be used with open sights, which are adequate for short range and instinctive (read defensive) shooting. By the time most folks can afford African hunting, they've gotten on in age, and may no longer have the eyesight necessary to use open sights. Yes, you can add a scope or holo sight to a double, and hope that the addition doesn't affect the regulation of the rifle. But when equipped as such, why not just use a bolt rifle?
The one area where doubles are in their realm for a hunter is in Elephant hunting, where ranges are short and the availability of 2 quick shots is a good safety net.
As I said, I love shooting and hunting with double rifles, even with their shortcomings. But I advise folks to think of it like bowhunting, where you're purposely limiting yourself to short-range shots, using you skills to get within close range of your quarry.
