Does powder weaken?

[claylake]

I started loading .45 ACP and having trouble meeting major until I went to the local gun show and bought a fresh AA N340 today. I tried N320 and could not get over 900 fps with a 185 HP. I switched to an old container (5 + years old) of N340 and with 6.9 grains only going 825 fps. I opened the new N340 and loaded to 7.3 gr. And went over 1080 fps. Switched back to the old powder at 7.3 and the speed was 857????? Does powder weaken over time? It was in the original sealed container.

[Jerry944T]

Stored properly it shouldn't lose any power. Of course different lots can be significantly different especially if you are measuring by volume.

[ClarkEMyers]

It might but I sure hope it takes more than 5 years; I routinely use powder older than that myself - folks have used powder from the 19th century in the 21st with good results - on the other hand duds all over the world and throughout the history of smokeless powder have gone click when folks expected a bang and bang when folks expected a click

-- The blast involved 98 barrels of confiscated Iranian explosives, largely gunpowder, that had been intercepted en route to Syria. It's not sure yet if the blast triggered a resulting brush fire, or a brush fire triggered the blast.

-- The barrels had been sitting in an open field at the Evangelos Florkis naval base for two years in temperatures that sometimes topped 100 degrees.

At least some lots of some powder loose moisture and so a given weight will have more or less moisture over time - that's an argument for measuring by volume not weight but once again it depends and YMMV

[bruce381]

same powder 340 or 320? you list both. But perhaps a bad lot? if it nvere made speed. if it did and now same can does not then Call mfg.

[Wrightturn]

I used to worry about it. If it doesn`t smell like vinegar I use it. If the chronograph shows the right numbers I keep using it. I was unable to shoot due to health reasons for about 6 years. Powder stored in a hot Florida garage has worked fine despite being over 20 years old.

I have noticed certain powders with a strong solvent odor seem to lower velocity after the solvent evaporates. I used to pour out 700X for 24hrs to let the solvent evaprate and the powder to absorb moisture before loading. Velocity would drop about 10% but sd would be lower and es would be single digit.

I have half a square can of Bullseve that i bought in 1966, I won`t test it in any of my 1911`s. I have a TC Contender in 45acp and ????????


Wrightturn

[claylake]

Originally Posted by bruce381

same powder 340 or 320? you list both. But perhaps a bad lot? if it nvere made speed. if it did and now same can does not then Call mfg.

I only bought 340. I had old containers of 340 & 320 on the shelf. The new jug of 340 was only one i could get over 900 fps.

[Emerson]

Originally Posted by claylake

I only bought 340. I had old containers of 340 & 320 on the shelf. The new jug of 340 was only one i could get over 900 fps.

This sounds like simple variation from lot to lot. I seriously doubt 5 year old powder that had been stored properly would lose its oomph.

[WESHOOT2]

How do I know?

Because I lot my ammo, and some of it, made with powders older than many here, gets regular chrono-testing to confirm unifirm behavior (no I AIN'T ANAL; onceuponatime it was just part of my job, and that habit ain't died).

Most of my powders are over ten years old, and some significantly older.
I have a still-significant amount of one certain powder, aged for now-fourteen years, and each 3lb can performs like the one just emptied.

One caveat: Storage conditions matter. ESPECIALLY with Vihtavuori powders......

[mil-dot]

Originally Posted by Wrightturn

I used to worry about it. If it doesn`t smell like vinegar I use it. If the chronograph shows the right numbers I keep using it. I was unable to shoot due to health reasons for about 6 years. Powder stored in a hot Florida garage has worked fine despite being over 20 years old.

I have noticed certain powders with a strong solvent odor seem to lower velocity after the solvent evaporates. I used to pour out 700X for 24hrs to let the solvent evaprate and the powder to absorb moisture before loading. Velocity would drop about 10% but sd would be lower and es would be single digit.

I have half a square can of Bullseve that i bought in 1966, I won`t test it in any of my 1911`s. I have a TC Contender in 45acp and ????????


Wrightturn

I'm interested to see what the 1966 powder burns like...

[Wrightturn]

Hey Mil

Will let you know. I didn`t own a chronograph in 1966 but will be interesting to compare with current data. I have some old GI ball from WW2 that was supposed to be loaded with 5.0 under a 230 fmj. Something to do

Wrightturn

[brickeyee]

If not stored in a sealed container it can absorb moisture based on the humidity.

This increases the weight of the powder, resulting in less actual powder in each load.

[Wrightturn]

Ok re 1966 Bullseye. Son-in -law has my 45 acp Contender barrel. Loaded 3.0 gr in 38spl brass loaded 10 rnds and fired in 10 inch 357 Contender. Velocity avg 818 fps. Spread 19 fps. Same load I used in a S&W M52 around 1968. Any test from this point would be subjective. Despite improper storage seems to be fine.

[Twinkiethekid]

I always wondered too if the powder gets weak.

[ghitch75]

i have some IMR 4227 from the 80's and it's just as hot as it was then...