Howdy
Sorry about your experience with your Schofield Model of 2000.
Guy who sold it said they were too well made (too tight) to shoot black powder.
He did not know what he was talking about. The Model 0f 2000's inability to shoot Black Powder very well is all about the bushing pressed onto the front of the cylinder, nothing else.
This is a photo showing the prominent bushing pressed into the face of an original Schofield that left the factory in 1875. Notice how far the bushing protrudes from the face of the cylinder. About .165 from the front face of the cylinder.
The next photo shows how the cylinder lines up with the cylinder arbor. The extractor rod fits inside the hollow cylinder arbor while the bushing will ride outside the arbor.
In the next photo the cylinder is about 1/2 way to being fully seated. Notice the bushing can be seen riding on the outside of the arbor. Also, notice the helical groove cut into the cylinder arbor,
The cylinder is fully seated in this photo. The upper arrow is pointing to the front face of the cylinder, the lower arrow is pointing to the front face of the bushing. Black Powder fouling blasted out of the barrel/cylinder gap of any revolver blasts out pretty much in a plane. The .165 or so separation of the front of the bushing from the barrel/cylinder gap provides enough horizontal separation that the arbor is shielded from most of the fouling blasted out of the b/c gap. In addition, the helical groove cut into the cylinder arbor provided clearance for any fouling that managed to get past the bushing. Fouling would tend to accumulate in the helical groove and not bind up the cylinder.
By the way, ALL five of the original #3 Top Break revolvers made by Smith and Wesson; the American Model, the Russian Model, the Schofield Model, the New Model Number Three, and the 44 Double Action had a bushing like this pressed onto the front of the cylinder. The design worked very well, I bring a couple of New Model Number Threes to CAS matches about once a year and I can shoot them all day long with ammo loaded with Black Powder with no binding at all.
Recently I was able to examine a couple of the Model of 2000 Schofields in a local shop, Yes, he had two of them. Of course the shop was not going to allow me to remove the cylinder for a look at the bushing, but it was plain to me there was a very minimal bushing on the front of the cylinder. Here is a photo of one from the web:
Here is a photo of one of my original antique Schofields showing the arrangement of the cylinder bushing and how far forward it sits of the barrel/cylinder gap. I have no idea if the Model of 2000 includes the helical clearance cut on the cylinder arbor. The lack of one would contribute further to them binding quickly when fired with Black Powder cartridges.
Historically, what happened was all the original S&W Top Break revolvers had cylinders 1 7/16" long. This was the perfect length for the cartridges S&W was making for them at the time, the 44 S&W American round and the 44 Russian round. When S&W approached the Army about a government contract, the Army specified they must be 45 caliber. Up until that time all the S&W Top Breaks had been 44 caliber. S&W had no problem opening up the bores from 44 to 45. But the only cartridge the Army was using at the time was the 45 Colt cartridge, which was too long for a 1 7/16" long cylinder. S&W did not want to change the tooling for their frames and cylinders since they were in the middle of selling over 150,000 Russian models to the Russian, Turkish, and Japanese governments. So a compromise was reached allowing a shorter 45 caliber cartridge that would fit into a 1 7/16" cylinder. Thus, the 45 Schofield cartridge was born.
In the modern era, when ASM and later Uberti started making replicas of the Schofield model, they lengthened the cylinder to be able to accept cartridges such as 45 Colt and 44-40. They did not lengthen the frame a similar amount, instead they chose to shorten the bushing on the front of the cylinder, which is why the modern replicas tend to bind when fired with Black Powder. The guy in the shop was puzzled when I pulled out a tape measure to measure the cylinder on the Model of 2000 Schofield. He probably thought I was going to measure the length of the barrel. Nope, the cylinder was 1 7/16" long just like the originals. Except S&W clearly decided no one would be interested in shooting Black Powder from this model so the bushing on the front of the cylinder (yes, there is one) was much too short to keep fouling from accumulating on the cylinder arbor.
Frankly, I'm surprised your 200 grain bullets are shooting low. My experience with Top Break S&W revolvers is they tend to shoot high because the front sights are so short. When shooting my NM#3s at a SASS match I have to remember to hold low or my bullets may go right over the target.
I designed the 200 grain Big Lube bullet that you bought from Mark Whyte. That's why it is called the J/P 200, the J stands for Johnson. I designed the bullet a bunch of years ago when the only 45 caliber Big Lube bullet in existence was the 250 grain PRS bullet. I wanted a 200 grain bullet to shoot in my 1858 Remington with a cartridge conversion cylinder. You might try the 250 grain PRS bullet if you want to raise your point of impact, but as I said, all my S&W Top Breaks already shoot high.
I have never fired anything other than real Black Powder in my #3 Top Breaks, so I cannot comment on how much fouling you will get from the substitutes. I have loaded up some 38 S&W with APP for one of my smaller Top Breaks. The selling point of APP is it does not require special soft bullet lube as real Black Powder does. So standard modern smokeless bullet lube can be used with APP. If you can find some APP you might do better, particularly if you continue to use Mark's BP lube on your bullets.