Howdy
I am not at all sure the 45ACP was created to duplicate 45 Schofield performance. I suspect the similar bullet weight of 230 grains for both cartridges may be nothing more than coincidence.
45 Schofield was a cartridge conceived out of convenience by Smith and Wesson because the standard 1 7/16" long cylinders they were using for their #3 Russian revolver was too short to accept the 45 Colt cartridge. Colt had already obtained government contracts for the Single Action Army, chambered for 45 Colt and S&W did not want to be totally left out of government contracts. The government specified they required a 45 caliber cartridge, and S&W would have no trouble opening the bore up of their 44 caliber Top Break revolvers to .45. S&W was heavily invested in producing what eventually turned out to be over 150,000 Russian model revolvers for the Russian, Japanese, and Turkish governments, and did not want to incur the expense of changing tooling for a longer cylinder and longer frame to accommodate the longer 45 Colt cartridge. So the government agreed to accepting the shorter 45 Schofield cartridge with the S&W Schofield revolver.
For comparison, this photo shows two 45 Colt cartridges on the left and two 45 Schofield cartridges on the right. The two cartridges on the outside are my own reloads, the two in the center are original Benet primed, folded rim, copper cased cartridges. I can explain more about that if you want.
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As far as powder capacity is concerned, only the Benet Primed 45 Colt second from the left in the photo above actually contained 40 grains of Black Powder. Later, the Balloon Head cases had slightly less powder capacity. Modern solid head brass has even less capacity, I generally only load about 35 grains of powder into my 45 Colt cases with modern solid head brass. Here is a photo of a Balloon Head, or Semi-Balloon head as some call it 45 Colt on the left and a modern solid head 45 Colt on the right. I cut both in half to show the comparative powder capacities.
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Regarding 30 grains of powder in the 45 Colt cartridge here is a box of twenty cartridges manufactured at the Frankford Arsenal in 1874. As can be seen on the box, they contain 30 grains of powder. The Army was pretty much the main customer for the reduced charge 45 Colt rounds, it was felt there was too much recoil with the 38 or 40 grain loads in a revolver, although 40 or 38 grain loads were available commercially.
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I am really not sure what you are trying to accomplish. Are you trying to load the 45ACP with Black Powder, or are you trying to duplicate 45ACP performance with Black Powder in 45 Schofield brass?
I can tell you that it will be pretty useless trying to run 45ACP cartridges loaded with Black Powder through a 45ACP Model 1911 Semi-Automatic pistol. Successful development of Semi-Automatic and Full Automatic firearms pretty much depended on the development of Smokeless powder around the Turn of the Century. Black Powder cartridges simply cause too much fouling to be successful in fully automatic or Semi-Automatc firearms, they tend to bind up quickly from the fouling. In Cowboy Action Shooting we have a category called Wild Bunch where the 1911 is the standard pistol used. Of course, most competitors are shooting Smokeless in their 1911s. There have been a few guys over the years who have successfully loaded their 45ACP cartridges with Black Powder for competition, but certainly not with full metal jacket bullets. Real Black Powder, and some of the substitutes require special soft Black Powder Compatible bullet lube to keep fouling from building up in the bore.
For my Black Powder 45 Schofield ammunition I put in about 28 grains of Schuetzen FFg powder under a 200 grain bullet. Sorry, I have no chronograph data for you about what velocity these cartridges generate. How much powder capacity any case has is also dependent on bullet design. Some bullets extend further into the case than others, so they will cut down on powder capacity over a bullet that does not extend as far in.
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The bullet I use for 45 Schofield is the Big Lube 45 JP-200 bullet I designed a number of years ago. It is third from the left in this photo. Next to it on the right is the Big Lube 45 PRS 250 grain bullet. I designed my 200 grain bullet years ago when the only 45 Big Lube available was the 250 grain version. You can see that there is a bit less distance from the crimp groove to the bottom of the bullet on my 200 grain bullet than the 250 grain bullet, so it will allow a little bit more powder capacity in any case it is loaded into than the 250 grain bullet.
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The other thing to take into consideration is that not all Black Powder weighs the same. I came up with this chart years ago for the several different powders and granulations I was using in a few Black Powder cartridges. For standards I use the volume measurements supplied by Lee dippers, which are calibrated in Cubic Centimeters. The 1.9CC measurements are what I use in 45 Schofield. As can be seen, Elephant FFg, which is no longer manufactured, is the heaviest. My 1.9CC charge of Schuetzen comes to about 28.5 grains.
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I have no experience with Old Eyensford so I cannot comment on it.
Regarding 30 grains overflowing a case, I doubt it. I have not tried to put 30 grains of anything into a 45 Schofield case, but I suspect I could easily get about another 1.5 grains in without it overflowing and without compressing the powder too much. My standard compression is about 1/16" - 1/8" when the bullet is seated. I suspect I could easily fit in 30 grains with just a little bit more compression. But I doubt if an extra 1.5 grains will boost the velocity up where you want it.
And I certainly would not worry about 30 grains of any Black Powder not shoving a full metal jacket bullet completely out of the barrel.