Quote: I like a longer tube to get the muzzle blast a bit furthur away.
Muzzle blast is a function of several factors including expasion ratio, powder burning rate, bullet weight, and barrel length. A cartridge with a high expansion ratio, such as the .458 WM, using fast burning powder, such as IMR 4198, and 500 grain bullets, will not produce objectionable muzzle blast in a 22" barrel, in my opinion.
Just as important, that combination will leave no unburned powder in the barrel, which indicates that combustion is complete by the time the bullet exits the muzzle.
I have pre-64 Model 70 in .450 Watts with a 22" barrel, which is much more pleasant to shoot from the standpoint of muzzle blast than, say, a .264 WM with a 25" barrel, using H4831 and a 120 grain bullet.