Have you looked at the Brass casings for the .454 Casull? The ones I have seen have the thicker walls we see in the .44 magnum casings, not the thinner walls of the .45 colt, or .44-40.
Ruger, and now Smith & Wesson have come out with their huge, heavy, revolvers, to cut down on the Products Liability lawsuits they have been plagued with when people overload these older cartridges and the revolvers designed to digest them. The " More is better" crowd is KNOWN to immediately run out and buy these BIGGER, BETTER guns, and those cartridges, and stop abusing the older designs. Its a business decision made to keep the company in business that they have chambered the Super Blackhawk, the Redhawk, and the new .500 S&W revolver-whatever its called-- to seduce those shooters away from these other strong guns. The stronger heads on modern cartridges, makes a huge difference in how much pressure these revolver chambers and recoil shield can stand. The .44-40 and .45 Colt both date to 1873, and Balloon head casings were common up until WWII. The .44 spl. came to us in 1907, and the .44 magnum in 1956. Dick Casull came out with his hyped up cartridge in the 1980s, if memory serves me well But there have been more cartridges in that caliber brought out since.
The .45 colt cartridge, shooting a 200 grain HP bullet, at about 1,000 fps makes a wonderful social defense load, with minimal muzzle rise, and recoil to interfere with getting back on target. There is no need to load it up to 1,500-1,600 fps, particularly when we have stronger, heavier guns and cartridges that are designed to work at those velocities.
Trying to use 200 grains of powder in a short barreled Blunderbuss with a 14 gauge brass barrel is simply Dangerous, and there is NO NEED to do so, considering the limited effective range of that style of firearm. As someone has already noted, correctly, This load of powder in that gauge is well above even proof loads.
This is off-topic, so if you want to discuss this further, send me a PT. Thank you. The Moderators will also thank you.