In 1956, when Winchester introduced the Model 70 African in .458, it had a 25-inch barrel. This was the brainchild of engineers who had never been to Africa, or were insane, or both. It was very quickly chopped back to 24 inches, and is now available in 22 or 24. What you lose when you cut back a barrel is velocity--usually far less than you think. When I had my .338 RUM cut from 26 inches to 23.5, I lost something like 38 fps, and it no longer took five minutes to pull the rifle from a saddle scabbard. The other drawback to a short barrel is muzzle blast. A .30/06 with an 18-inch barrel, for example, is unbearable.