I thought of Trail Boss, but despite it's low velocities, it seems to have smokeless pressures. The worst of both worlds.
Howdy
First, I would like to say something about Trail Boss.
Because of the name, many shooters assume it is a Black Powder substitute. It is not.
Trail Boss was developed about 15 or 20 years ago pretty much exclusively for use in Cowboy Action Shooting. Many shooters in CAS download their cartridges a tremendous amount, (a ridiculous amount in my opinion) to reduce recoil and allow faster follow up shots. Down loading large capacity cases, such as 45 Colt, 44-40, 38-40, or even 38 Special, with charges below the recommended minimum charges in the loading manuals can cause unreliable results. The large amount of airspace left in such loads can lead to spotty and inconsistent ignition. With position sensitive powders this can get even worse. So Trail Boss was developed for reduced loads in large capacity cases.
As can be seen in this photo, the grains of Trail Boss look like flattened little donuts. They are not typical flake powders, the grains are thicker than most other flake powders. That may or may not be evident in this photo comparing a small pile of Trail Boss to a small pile of Unique. But the up shot is, a very light charge of Trail Boss will fill up a large capacity case, such as 45 Colt much more than a very light charge of most normal flake powders, such as Unique. One benefit of the case filling aspect of Trail Boss is it is more difficult to accidentally double charge a case than with other powders. No, it is not impossible, depending on the case and the charge, but it is very likely a double charge of Trail Boss will overflow the case and catch the attention of a reloader, while a double charge of something like Bullseye might go unnoticed. Again, that was not the primary reason Trail Boss was developed, it is a side effect. The reason Trail Boss was developed was so light charges could be loaded in large capacity cases without a large amount of airspace inside, for reliable ignition.
Trail Boss has been on the market a fairly long time now, and shooters other than CAS shooters use it. But because of the name, and because many shooters assume most CAS shooters use Black Powder (they do not) many assume Trail Boss is a Black Powder substitute. As I said before, it is not. As the label says, Trail Boss should never be used as a Black Powder Substitute in muzzle loaders, which includes Cap & Ball revolvers.
OK, back to the main subject.
I NEVER put any modern Smokeless powder into any of my 19th Century revolvers. NEVER! Colt specifically did not warranty the Single Action Army for Smokeless Powder until 1900. By 1900 Colt felt the steels they were using were sufficiently strong enough to withstand the pressures of Smokeless Powder. It is a bit more hazy with Smith and Wesson, there is no line in the sand regarding when their revolvers were safe to shoot with Smokeless Powder. However since S&W was just about 25 miles up the Connecticut River from Colt, I suspect they had access to the same quality steels as Colt did.
No, it is not all about peak pressure. I hear all the time how modern manufacturers are manufacturing some of the old cartridges with reduced pressure because of all the old guns still out there. It is not just about pressure. It is also about the pressure curve. Suppose you want to tow a car and all you have is a rope. If the rope is strong enough you can tow the car by starting very slowly and accelerating gradually. But if you start with a jerk, the rope is likely to break. The difference is in how the pressure was applied. Black Powder has a very long pressure curve. Most Smokeless Powders have a very short pressure curve, more of a spike. Even if the peak pressure of the spike in a Smokeless load is kept the same or below the peak pressure of a similar Black Powder load, the old steel may not be able to take the shock. There is a guy over on the Smith and Wesson forum I argue with all the time about this. He maintains there are Smokeless Powders that can be loaded to duplicate not only the pressure, but the pressure curve of a Black Powder load. He is probably correct. However I do not have pressure sensing equipment to experiment with, and I am not going to use my antique revolvers as guinea pigs.
So.
I load cartridges with real Black Powder all the time for CAS. I usually shoot a pair of 2nd Generation Colts, which would be fine for either Smokeless or Black Powder. But sometimes I bring this almost matched pair of antique Smith and Wesson New Model Number Threes. This photo was taken at the end of a match. They are still very sooty. They get cleaned when I get home.
Or I might bring this antique Merwin Hulbert along with one of the Smiths. This photo was taken before the match, the revolvers are still clean. Again, only Black Powder loads, Smokeless never gets near these guns.
Which begs the question, did somebody shoot these old guns with Smokeless ammo before I got them? Very likely. Still, I am not going to risk it with my antiques, they only see Black Powder ammunition.
As an aside, I will sometimes shoot an antique rifle with light Smokeless loads, but that is because the chamber walls of a rifle are much thicker than the chamber walls of a revolver, and an antique rifle IN GOOD CONDITION can usually take mild Smokeless loads.
Because of local storage requirements, many localities do not allow real Black Powder to be stocked or sold. Real Black Powder is classified by the BATF as an explosive. A low grade explosive, but an explosive none the less. So many communities do not allow it to be sold. Black Powder substitutes, such as Pyrodex or Tripel Seven are classified differently by the BATF and the storage regulations are the same as for Smokeless Powder. So the subs are more easily available to many shooters.
The only Black Powder Substitute I have any experience with is American Pioneer Powder. Also known as APP. Unlike real Black Powder, and many of the other substitutes, APP does not require a Black Powder compatible bullet lube. It can be used with standard smokeless bullets lubed with modern hard wax lubes. I bought some APP a bunch of years ago because I wanted to load some 38S&W (not 38 Special) ammo with Black Powder for one of my antique pocket pistols. I wanted to use some easily available bullets, so I loaded up a couple of boxes with APP. It worked fine, however my experience with it is very limited.
When I load with real Black Powder I usually use Schuetzen. Schuetzen uses a better grade of charcoal than Goex, and produces slightly less fouling than Goex. Loading up a batch of 45 Colts here into shiny new brass. The bullets I use are the Big Lube bullet series that have a huge lube groove filled with a specific Black Powder compatible bullet lube.
Cleaning guns after shooting with Black Powder is easier, but more messy, than cleaning after shooting with Smokeless powder.
A subject for another time.
(P.S.) I seldom clean my guns the same day after shooting them with Black Powder. They do not turn into piles of rust over night. Old fashioned corrosive primers and Black Powder fouling were a bad combination. Modern primers are not corrosive, and the fouling produced is far less corrosive than most shooters believe.
