I wandered into the Western Powders booth at shot, and I'm not really sure how, but we ended up with an in depth interview on Blackhorn 209.
The powder is a Black power substitute, suitable for inline muzzle loaders, and cartridge guns.
It's claims are:
Lowest standard deviation in the industry
Consistently higher velocities with peak accuracy
Non Corrosive and low residue. (They still recommend you not leave your barrel uncleaned after the match)
No 'crud ring' to distort sabots etc
No swabbing between shots
Easy breech plug removal (less residue on the plug)
Standard 209 primers are all that is required. Special Muzzle loading 209's are not recommended, and may not work as well as standard primers.
Temperature stable, non hygroscopic
Uniform grain size
Clean up with standard oil based cleaning solvents, NOT water.
Below is a pic of recommended breech plug designs.
The one plug by itself is the not recommended design,
Apparently there is an ignition issue with that design.
Not sure what happened to my pic, it's just gone, but you can get info from the website.