Single base vs double base powders

[Calvin45]

asking for your opinions and experiences regarding differences between single and double base propellants. The double base (nitrocellulose and nitroglycerin, the alliant reloader series, the new imr enduron powders) in theory are capable of higher muzzle velocities across the board but the single base (all the old school Hodgdon and imr powders - 4064, 4350, 4831, 7828, h1000) should in theory be capable of tighter sd and es numbers simply because their simpler and therefore almost certainly more uniform. Is there actually any difference on either front in your experience? Accuracy, velocity, consistency...

 

[BallisticsGuy]

It used to be that simple, there NC and NC/NG and that was that. You could actually make statements about one or the other and have them be verifiable or falsifiable. In more modern times though the high energy compound component isn't nearly as relevant to propellant performance as some of the other ingredients that have been put in to tweak performance which have pretty much rendered a lot of the old wisdom so full of exceptions and qualifications that it's kinda meaningless to discuss powders simply based on them containing NG or not. That doesn't even address more modern energetic materials like nitroguanidine and others that have made it in to modern powders.

 

[Calvin45]

It used to be that simple, there NC and NC/NG and that was that. You could actually make statements about one or the other and have them be verifiable or falsifiable. In more modern times though the high energy compound component isn't nearly as relevant to propellant performance as some of the other ingredients that have been put in to tweak performance which have pretty much rendered a lot of the old wisdom so full of exceptions and qualifications that it's kinda meaningless to discuss powders simply based on them containing NG or not. That doesn't even address more modern energetic materials like nitroguanidine and others that have made it in to modern powders.

Very intrigued by your comments here...I know about nitroguanidine being in triple base powders for cannons and such but didn't know it was in any commercial small arms reloading powder. What specific powders are triple base/contain nitroguanidine in such quantity as to affect interior ballistics and not just as a flash suppressant? Appreciate the feedback, as always it would seem things aren't as simple or straightforward as one would think.

 

[BallisticsGuy]

The reference was to the fact that small arms powders as a category have undergone a large set of changes from the more primitive formulations of days gone by, not specifically to nitroguanidine's impact or commonness. I don't recall the specific powder I've seen it included in while reading data sheets for fun but it intrigued me to find out about it when I did. If I recall correctly the last reference I saw to it was it being included in single digit percentages by weight. Nitroguanidine is said to accomplish the flash reduction, flame temperature reduction and a reduction in chamber pressure for all that; which is like magic when you think about it, so I'd assume (yes I know about assuming) it has to have some effect on how it responds to things like environmental/ammo temperature.

 

[Calvin45]

Interesting. I know that nitroguanidine is much slower to burn but also read that once it is, the gas expansion velocity is actually higher than cellulose or glycerin. I believe it was never used historically for small arms because the burn rate was too slow for anything, hence its use in triple base cannon powder. With the rise of so many overbore magnums I wonder if there'd be a use or market for triple base powders. I don't know enough about any of that to feel I'm actually on to something, but still... perhaps we'd start pining for .30-408 cheytacs or 6mm rums.