In the late 1950s, Winchester came out with the 264, 338, and 458 Winchester Magnums. In 1962, Remington used the same cartridge case for the 7mm Remington Magnum. The case is essentially the basic belted number that has been around since 1912 as the 375 H&H Magnum but, instead of being left full length at 2.82 to 2.85 inches (depending on which full-length belted magnum you're talking about), the case was shortened to 2.50 inches to make the new generation of short magnums. Weatherby had already been producing shortened magnums since the mid-1940s, but never mind that. And never mind the late 1950s development of the 308 and 358 Norma Magnums.
The main purpose of the shorter magnums was that more power could be stuffed into cartridges with the overall loaded length of 3.34 inches, and therefore fit and feed through a standard-length action. That required the cartridge cases to have less body taper than the 375 H&H, which allowed for more powder capacity. The reason I'm focusing only on the commercial shorter magnums of the "big two" is because it is that original 1956 entry, the 458 Winchester Magnum, that serves as the basis for the 416 Taylor. It is, essentially, the 458 necked down to 416, and then blown out for less body taper. Another approach is to neck up 338 Winchester Magnum cases, which already have the correct body dimensions. However, the "blow-out" is no big deal, which is the beauty of headspacing on the belt, which is essentially a rim moved forward a little ways. Think about it.
Robert Chatfield-Taylor thought about it, and necked up the 338 Winchester Magnum to 375 to make what became known as the 375 Chatfield-Taylor, and later the 375 Taylor. I built a rifle for this cartridge in 1970 using a Model 70 action and Douglas barrel. Some questionable math (all of my math is questionable) dictated that the barrel be 23 inches. All of that worked out very well, and I was able to pretty much duplicate 375 H&H performance with no signs of pressure problems. The rifle shot well, I could shoot it well, but a problem developed. The fabulous Fajen stock, and the fact that a lot of other people also could shoot it well, led a few other big-bore fans at the range to make generous offers for the rifle. One of them offered too much, and I sold it. Many years later, I was told that his son had taken the rifle to Africa, but was denied its use on safari because his ammunition for it was headstamped "338 Win Mag" instead of the "375 CT" as on the barrel. I felt better knowing that.
I suspect that Taylor's work with the 416 came somewhat later than the 375, and it has been reported by others that the 416 Taylor first appeared in the early 1970s, which was later than my first introduction to the 375. Anyway, it then became a loose plan to someday build, or have built, a 416 Taylor. This time the Chatfield half of his name was apparently dropped at the start. I planned to use a Winchester action again. Especially in recent years, the Model 70 action has just gotten better and better. Those of the last few years are nothing short of jewels. An egghead friend of mine went to the trouble to "lay out" (systematically and scientifically check dimensions) a few of the later actions, and his usual understated self simply said "very impressive."
You don't have to go to all the fuss of building a 416 Taylor; CZ offers it in their fine Safari Classics Express Rifle. This is one of their up-scale rifles that they build to order, so give them a call if you're interested.
Amazingly, the 416 Taylor is quite capable of sending 400 grains of bullet out of the barrel at 2350 fps at proper pressure. The full-length 416 Remington can better that by about 100 fps, but 2350 is a great plenty. In comparison, the great 404 Jeffery delivered 400 grains at 2170 fps (2125 fps in some data, 2300 fps in Hornady's current loadings). At even greater velocity, 350-grain pointed bullets such as the Barnes TSX or the Swift A-Frame will deliver a heavy blow and provide very useable trajectory for longer shots.
The 416 Taylor is capable of handling any game, and recoil is not all that much heavier than the 375 H&H. For the couple of handfuls of rounds that will be fired in a year, I recommend manning up to give it a try. What would have been a difficult obstacle regarding the proper headstamp for Africa is apparently no longer a problem, as both Doubletap and Norma currently list current production of the ammunition.