Triple-base gun powder?
Single and double-base smokeless gun powders are very common is all small arms cartridges. They are available for use by reloaders and factory produced ammunition.
The primary energy source in single-base powder is nitrocellulose.
The primary energy source in double-base powder is nitrocellulose and nitroglycerine.
The primary energy source in triple-base powder is nitrocellulose, nitroglycerine, and nitroguanidine.
Triple-base powders are used almost exclusively in larger arms such as artillery and are therefore restricted for civilian purchase.