Is volume is more accurate than weight, a personal observation

[jacobhh]

I don't know, factory ammo is pretty darn good nowadays

The question of scale weight vs. volume has been adressed many,
many times in this forum and it always ends up in many, many opinions.

Pure water is easy: 1 gm = 1 cc . Gunpowder? no solution.

Stay under the the published scale weight load, take all special precautions
for gas guns and you'll probably be OK. Black powder by published volume.

If you want to be 'accurate', consistency is always the answer. Super
accuracy lies in concentricity and the shooter. Factory ammo is now
good because it's round and straight, match that and your good.

Don't forget to throw away your questionable brass.

My 30 year opinion.

 

[Varminthound]

I have a question about balance scales. If I balance the scale and do nothing with it for a day or two the scale is not in balance when I come back to it. My solution is to re-zero the scale an verify it with a digital scale. Why does the balance change? The scale is on a very firm surface with no extraneous virbrations. Is it a faulty scale or does a changing barometric pressure shift it? I believe the latter.

Am I way off base here?

 

[rogn]

god balanc scales are very suseptable(?) to dust , finger prints and other forms of grime. If you want to see the effects of grime or finger prints, weigh several dozen loads and recheck your zero, then carefully wipe off the pan with an alchol moistened tissue and recheck- youll be surprised. Keeping a good camel hair lens brush handy to clean off the beams and knife edges will benefit the scale in the long run.

 

[MCMXI]

Is it a faulty scale or does a changing barometric pressure shift it? I believe the latter.

As atmospheric pressure changes, all parts of the balance will be exposed to the same change so the balance should still be in equilibrium ... unless half of your balance is in a different zip code. Which way does your balance shift? Is it in the same direction each time? I would guess that your work surface isn't quite level ... it may be ever so slightly off?

 

[Varminthound]

I'll check for a few days and let you know if it only goes one direction. I think it erratic though but I want to check it out for a few days.

 

[jerkface11]

Of course volume is more accurate. Granules of gunpowder absorb water. This changes their weight. It doesn't change their size.

 

[MCMXI]

This changes their weight. It doesn't change their size.

Oh really!! Try telling ANY woman on the planet that her increase in size each month ISN'T due to water!!

 

[cracked butt]

Oh really!! Try telling ANY woman on the planet that her increase in size each month ISN'T due to water!!

I'm risking thread lock here, but strangely the volatility also goes up, balancing out the increase of volume

 

[GaryL]

In any chemical reaction that produces energy, it is the mass that is converted to energy, i.e. the quantity of molecules available for conversion and the conversion efficiency (incomplete vs complete combustion). We use weight to determine mass, which is reasonably accurate for most situations. Assuming powder is hydroscopic (absorbs moisture), what are we talking about for % of weight? 5% maybe? Probably not that much actually. How much does the humidity vary at any given time? From winter to summer in MN, it's a pretty big change, but that doesn't mean that the amount of moisture the powder will absorb and release is directly related to humidity 1 for 1. In other words, a 50% atmospheric change may only be 25% of 5% (or 1.25%) change in weight in a non-condensing environment. (The implied warning here is to allow the container to reach ambient temperature in the reloading environment before opening the container and dispensing any powder). In any kind of controlled environment (air conditioned and heated), I'd be very surprised if the change in weight due to water absorption even approached 0.5%. The density of a volume of powder, on the other hand, is the real issue, as discussed earlier, and that can vary significantly.

I might also add that more attention should be given to conversion efficiency, which is influenced by the type of powder chosen for the application, volume of case, crimp, distance to lands, and all those other factors that we think of as affecting accuracy, but really also relate to the burning of the powder and the rate at which pressure is generated.

 

[Gewehr98]

I'd have to disagree with that.

Stay under the the published scale weight load, take all special precautions for gas guns and you'll probably be OK. Black powder by published volume.

Real black powder (aka, Holy Black) is fine measured by weight, as all the volumetric powder measures intended for that propellant are graduated based on the same weight of BP. IOW, 70gr of BP on a scale will fill a 70gr BP measure perfectly. It's the nature of the product, and is somewhat unique in that aspect.

However, folks will run into trouble when trying to measure BP substitutes like Pyrodex using Holy Black graduations. They're not interchangeable.

 

[Varminthound]

I found the answer on another thread here. Apparently the cell phone was too close and I suppose magnetic influence caused inconsistent readings. All I could think of was baromtric pressure. You know the column of air above the pan that had greater area than the beam. I moved the phone and the scale hasn't moved from zero. lol

 

[MCMXI]

You know the column of air above the pan that had greater area than the beam.

If the balance was in a state of equilibrium (zeroed) and then the atmospheric pressure changed, wouldn't the balance STILL be in a state of equilibrium since the change would be the same for all parts of the balance ... just a thought.

I moved the phone and the scale hasn't moved from zero. lol

.... one of the reasons why my wife (who uses her cell A LOT for work) uses a bluetooth headset rather than slap that tumor generating device right up to her noggin.