It's great to have someone with experience here, thanks for contributing! The issue with nitrocellulose is that it is expensive to produce and gunpowder is already available. Maybe adding a percentage to the GP will make it stronger, still possible to use in the muzzleloader and at a much lower cost... What proportion do you consider ideal? But I think the search here is to find a product that is easy to make at home and that is independent of the arms industry. We should look at the advantages of GP, a cheap, easy to make and clean propellant. If you want more strength, increase the dose of powder!