Do nitroglycerin containing powders lose muzzle velocity over time?

[Cassidy]

The reason I ask this question is that nitroglycerin sublimates; it essentially evaporates if left to just sit there in an open container or a container that is re-opened a number of times. Some powders, including the VV N550 and VV N540 that I use, contain nitroglycerin. My understanding is that the extruded granules in these powders have some sort of sealer that may be there to help prevent the nitroglycerin from sublimating when the container is repeatedly opened. If the nitro sublimates, then muzzle velocity might be lost if the powder is not totally used within a period of time. Anyone know if this occurs?

Cassidy

 

[amlevin]

"Nitro" evaporates? Wow. I wonder how all that dynamite we used to store in a shed on the farm lasted so long and still moved stumps? The big problem we had was making sure the stuff didn't "sweat", not evaporate.

I had a "can" of 2400 that I used pretty slow. Took me about 15 years to use it up and every one of the .357 loads were just as fast at the end as in the beginning of the can.

 

[Laurie]

I pulled a big load of 1943/44 dated Winchester .30-06 M2 ball ammo maybe 10 years ago so the ammo was getting on for 60 years old and had NOT been stored in good conditions. The ball powder looked and smelled like new. Other WW2 era M2 ammo in the same box of scruffy rubbish that used stick powders (IMR 4895 presumably ?) had had their charges turn into a black goo with only a few remains of the kernels still visible. In some cartridges, this deteriorated powder had corroded the cases from the inside so badly that the brass would tear apart when using a collet puller in a press.

This must have been very early Winchester-Western ball powder as the production process was introduced in the 1930s. All ball / spherical powders are double-based. Anyway, this stuff had lasted so well I was almost tempted to try it in a few cautious .30-06 test loads, but sense prevailed. Even though it looked good, it may have suffered hidden chemical changes that would affect pressures.

 

[jonbearman]

I have a cardboard can of hodgdon 4831 I bought from a local gunshop called creekside.They said you were on your own.They opened a few cans and it looked good and smelled great.I have since transferred it into a plastic container(an old powder bottle and relabeled it),the can said,reclaimed military powder from WWII.I have a pound or so left and covet it for my .243's.Basically stop worrying unless you store it in a shed where it is hot and humid.I store mine in a basement where it is cool and dry.I have powder that is decades old. If kept right you are good to go.

 

[Milo 2.0]

Cassidy,
I've been hearing more and more of this too. I've heard it called oxidizing. VV powders and certain Norma powders seem to have more Nitro in them than others, though I've never heard Norma mentioned in the velocity loss. I've seen it in the VV N 500 series. I try to load all open containers within a month time period to offset this, whether it helps, I don't know.

The people to talk to would be VV themselves. I'm sure they'd be more than happy to elaborate.

 

[CaptainMal]

When things "sublimate", they go from a solid to a gas directly. That's what dry ice does.

There would not be any "goo" in the can as there's no liquid stage. My guess is ...No.

 

[Webster]

I don't know anything about sublimation. A different issue is that nitric acid and sulphuric acid are used in the chemical reactions to make nitro cellulose and nitro glycerin. Two separate processes. The unreacted acids need to be removed from the nitro cellulose and nitro glycerin. Remaining acid leads to deterioration of the powder. I doubt it's as much of a problem as it was 50-75 years ago? I remember opening a can of powder 30 years ago. It smelled bad and it contained red dust.

The Alliant website discusses storage and deterioration.

http://www.alliantpowder.com/getting_started/safety/storage_handling.aspx#Anchor-How-47857

 

[jlow]

I don’t think nitroglycerine sublimates.

As CaptainMal mentioned, sublimation means a solid that does not go through a liquid phase before it goes into the gases phase – a good example being dry ice which is solid carbon dioxide.

According to “The Merck Index” which is an authority on chemical characteristics, monograph #6429, the stable form of nitroglycerine has a melting point at 13.5 degrees Celsius which is the same as 56.3 degree Fahrenheit. The fact that is has a melting point means that it will go into liquid form.

FWIW, it also says nitroglycerine will “begin to dec(compose) at 50-60 degree” which is equal to 122 to 140 degree Fahrenheit which is pretty warm and I suspect is the reason why most nitroglycerine containing powder is pretty stable at room temps. All bets are off if you leave it in the sun or some sort of location (like a trunk) which is not temperature regulated.

 

[Raythemanroe]

I think if your nitro had been evaporating and or condensating we would have read about it a few times (boom) just saying>

 

[bigedp51]

The very reason the military prefers double base ball powders is because they remain stable longer than single base propellants, and they can easily be recycled into new propellants.

 

[Webster]

Having a melting temperature doesn't mean it can not have sublimation. Look up sublimation on Wiki Definitions. Snow can have sublimation. You can hang wet clothes out to dry in the winter when its below freezing. Eventually they will dry. It has something to do with the vapor pressure of the substance. If sublimation of nitro glycerin took place I would think the manufacturer of the smokeless powder would have a use by date. I think they don't recommend storing for long periods of time but they don't explain why. I lot of the powders we buy are from reclaimed military supplies. I wonder how old they are.

 

[Cassidy]

Captainmal and jlow, you are right, nitroglycerin does not sublimate (vaporization from a solid); my mistake. Nitroglycerin is a liquid with a high vapor pressure, which means it vaporizes relatively easily. Same issue. If it vaporizes, it can be lost from the powder, so there is question of whether muzzle velocity might be reduced with time.

Good replies.

Cassidy.

 

[M14AMU]

I have a supply of ammo that my Dad and I loaded in 1948! Powder was $1.25 per pound!!

If it shot any better....I'd have an orgasm!! ;D

 

[jlow]

Having a melting temperature doesn't mean it can not have sublimation. Look up sublimation on Wiki Definitions. Snow can have sublimation. You can hang wet clothes out to dry in the winter when its below freezing. Eventually they will dry. It has something to do with the vapor pressure of the substance. If sublimation of nitro glycerin took place I would think the manufacturer of the smokeless powder would have a use by date. I think they don't recommend storing for long periods of time but they don't explain why. I lot of the powders we buy are from reclaimed military supplies. I wonder how old they are.

Nope!

I took the trouble to look up both "carbon dioxide" and "nitroglycerine" in the Merck Index and guess what sublimation is clearly spelled out for carbon dioxide but not nitroglycerine. It says “At atmospheric pressure the solid form changes into the gaseous phase without liquefaction” only for carbon dioxide.

For those interested, it is a function of physical chemistry which lays out whether this phenomenon will happen in a phase diagram. This is nasty hard core science and I am sure you guys don't want me to go into it - LOL!

 

[CatShooter]

This is nasty hard core science and I am sure you guys don't want me to go into it - LOL!

jlow...

Please don't ruin a "debate" that is rife with myths and suppositions, by introducing facts and hard science. That is against the rules on the internet.

I have 30 year old W-748 that yields the same velocities as current production - so, no, nitroglycerin based ball powder does not go bad.

 

[Raythemanroe]

Some of my best groups came from old powder, not 1948 but you know what I mean!