To get higher velocities in one of my loads, I had to use one of the slower-burning powders with available load data.
This 60% is inaccurate. Who said this? What it is, with black powder, too, is that all combustion doesn't always occur Inside barrel/cartridge. With smokeless powder, the methane produced is burning off when it hits the atmosphere. In black powder, it takes a long barrel for all the powder to burn efficiently. What doesnt ignites in the air, making that huge yellow or purplish flash. This is due to low Oxygen balance of powder. It could be improved with more oxidants, but that corrodes bores. Gunpowders are a necessary compromise. And, Double Based powders already Contain. GTN. (N****gly******)
The laws of physics do not suspend themselves for you.
That would be crazy. You aren't going to get a lot, no matter what you do, without increasing pressures past the safe range. You might, though, think about trying an appropriate propellant from the Vihta Vuori 500 series. These double-based propellants seem to produce pretty high velocities for the pressure curve. Another thing you might check, if you haven't already, is to see if you have enough leade in your rifle to load the bullet a little farther out, giving you a little more volume to work with. If you're looking for a couple of hundred fps improvement, though, you're on a search for magic, and you should just by a rifle with more cartridge.
