It would be burnt outside at about 2 degrees Celsius with about 75 percent air humidity, 1400 meters above sea level. Even though that's not exactly true, I'll treat it like pure guncotton. I'm asking myself questions like if I should use an initial explosion to heat it up and/or spread it out.
Fire requires three things: heat, fuel and oxygen. When burning a cotton ball, a match will provide heat, the cellulose fibers will provide fuel and the air will provide oxygen. It is the amount of oxygen in the air that causes the cotton to burn relatively slowly. By soaking the cotton in Sulfuric Acid and Nitric Acid, the hydrogens that were attached to the "spokes" of the carbon wheel are broken off and replaced by nitrogen and oxygen. Simply put, the spokes of the carbon wheel get more oxygen atoms stuck to them after a bath in strong acids. With all this extra oxygen, the cellulose can burn much more efficiently and will produce a quick, clean burning flame!
The name nitrocellulose gives a pretty good idea of the chemistry of the gun cotton. The "nitro" refers to the nitrogen groups that attach to the spokes of the glucose carbon wheel. Each of the nitrogens brings extra oxygens with it when it attaches. The "cellulose" of nitrocellulose refers to the cellulose fibers of the cotton. Hence the name "nitrocellulose".
Nitrocellulose is often found as a product called flash paper when 100% cotton paper is subjected to the same reaction. This paper is often used in magic shows as the magician is attempting to redirect the attention of the audience. It is available here and it is wiser to buy flash paper than to try to make your own!