Why and when to use Grain as a unit of weight measurement

[boyntonstu]

Grain (mass)
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For other uses, see Grain (disambiguation).

A grain is a unit of measurement of mass that is based upon the mass of a single seed of a typical cereal. Historically, in Europe, the average masses of wheat and barley grain were used to define units of mass, with the troy grain based on barley. Since 1958, the grain or troy grain (Symbol: gr) measure has been redefined on the basis of the unit of mass of the International System of Units as precisely 64.79891 milligrams.[1][2] Thus, there are precisely 7,000 grains per avoirdupois pound in the Imperial and U.S. customary units. In fact, the grain is the only unit of mass measure common to the traditional three English mass and weight systems (avoirdupois, Apothecaries', troy). Moreover, the measure for pearls and diamonds—the pearl grain and the metric grain—are equal to 1⁄4 of a (metric) carat, i.e. 50 mg (0.77 gr).


The grain is used to measure the mass of bullets, gunpowder, and smokeless powder; it is the measure used by the balances used in handloading; bullets are measured in increments of one grain, gunpowder in increments of 0.1 grains.[3] Moreover, the grain is used to weigh fencing equipment, including the foil. In archery, the grain is used to weigh arrows and arrow parts.

The grain is the most common unit used to measure the hardness of water. In particular it is used to quantitively describe the abundance of calcium Ca2+ and magnesium Mg2+ minerals in water. Typically, the measure is noted in grains per gallon (gpg). Water, untreated, typically can measure up to 100 gpg. This measure is critical to setting accurately that resin cation bead regeneration cycle perodicity of both sodium chloride brine and potassium chloride brine flushed water softeners.[clarification needed]

[MrCrowley]

Glad we can agree that the only appropriate time to use grains is when measuring the mass of bullets, gunpowder and smokeless powder.

edit:
And...fencing equipment, including the foil. In archery, the grain is used to weigh arrows and arrow parts.

[boyntonstu]

Glad we can agree that the only appropriate time to use grains is when measuring the mass of bullets, gunpowder and smokeless powder.

edit:
And...fencing equipment, including the foil. In archery, the grain is used to weigh arrows and arrow parts.

Sorry, I do not agree with 'only' and 'appropriate'.

I will use grains when I consider it appropriate.


To date, I have used grains to weigh projectiles, darts, and my piston.


Accuracy to 1/7000 of a pound is good enough for me.

[Lentamentalisk]

No. Precision is good enough for you. Precision is how fine your value is. Accuracy is how close to the real value your measured value is. Accuracy is entirely dependent on how good the measurement equipment is, not on how many decimal places it displays.

[/semantics] [/technicalities]

[boyntonstu]

No. Precision is good enough for you. Precision is how fine your value is. Accuracy is how close to the real value your measured value is. Accuracy is entirely dependent on how good the measurement equipment is, not on how many decimal places it displays.

[/semantics] [/technicalities]

The digital scale that I use is accurate to 0.1 grain.

I do not know of any scales calibrated in grains that would not suit air rifles.

You are correct in your definitions.

I used to work at the National Bureau of Substandards!

[velocity3x]

Sorry, I do not agree with 'only' and 'appropriate'.

OMG....I hope this doesn't spawn yet another drama thread debating the use of the words "only" and "appropriate"

[MrCrowley]

So we should all start using Torr instead of PSI because it is more precise? There are 51.7 Torr to 1 PSI. Or Pascals, there are 6,894 Pascals to 1 PSI.

I doubt anyone on Spudfiles has the equipment to accurately measure the performance difference between a piston weighing 540 grains and 555 grains, or a projectile weighing the same. When you put figures in to GGDT you don't write the diameter as 4.2291", or the orfice as 2.827", so why be so precise with the weight of a piston or projectile?

When I fire my cannons I don't use a gauge in Torr and stop exactly at 5171 Torr for 100PSI.

If you're going to use grains, list the weight also in grams or ounces. Stop being difficult.

[boyntonstu]

So we should all start using Torr instead of PSI because it is more precise? There are 51.7 Torr to 1 PSI. Or Pascals, there are 6,894 Pascals to 1 PSI.

I doubt anyone on Spudfiles has the equipment to accurately measure the performance difference between a piston weighing 540 grains and 555 grains, or a projectile weighing the same. When you put figures in to GGDT you don't write the diameter as 4.2291", or the orfice as 2.827", so why be so precise with the weight of a piston or projectile?

When I fire my cannons I don't use a gauge in Torr and stop exactly at 5171 Torr for 100PSI.

If you're going to use grains, list the weight also in grams or ounces. Stop being difficult.

When you list the weight in ounces, or grams, will you also include grains?

[velocity3x]

For a gun constructed of off the shelf parts with gigantic clearances / tolerances, it's seems kind of silly to obsess about the degree of accuracy used in weighting the projectile for said gun.

[MrCrowley]

The point is that we should all use units that are appropriate for the application and that are well known. Ounces and grams. PSI and Bar (or pascals even). Millimeters and inches.

As velocity points out, when the rest of your cannon is as about as accurate as anything built out of a garage, why do you need such an accurate measurement for piston weight or projectile weight?

[boyntonstu]

For a gun constructed of off the shelf parts with gigantic clearances / tolerances, it's seems kind of silly to obsess about the degree of accuracy used in weighting the projectile for said gun.

What are the tolerances of Type L copper tubing?

You may be surprised.

If there were no tight tolerances, how could a fitting made in California fit a tube made in China?


Is it you goal to build as accurately as you can, or are you satisfied to live with gigantic clearances?

[MrCrowley]

If there were no tight tolerances, how could a fitting made in California fit a tube made in China?


Is it you goal to build as accurately as you can, or are you satisfied to live with gigantic clearances?

None of which is homemade. How good are the tolerances on your pistons or homemade projectiles? Also the tolerances on pipe fittings aren't as good as you think they are.

If you projectile weighed 555 grains rather than 540 grains, it wouldn't make a bloody difference. Same with your piston.

[boyntonstu]

The point is that we should all use units that are appropriate for the application and that are well known. Ounces and grams. PSI and Bar (or pascals even). Millimeters and inches.

As velocity points out, when the rest of your cannon is as about as accurate as anything built out of a garage, why do you need such an accurate measurement for piston weight or projectile weight?

I never said that your ounce/gram weight is less accurate than using grains.

Grains are nice to use because that's how bullets are weighed.

Grains comes with the scale.

I don't convert to grains.

Another nice thing is that when I add a little hot glue to a dart, I can see that I added 4 grains.


It is easy to remember.


Much easier than a gain of 0.259 grams.

If grains were not useful, ask GGDT to discard it.

[velocity3x]

Is it you goal to build as accurately as you can, or are you satisfied to live with gigantic clearances?

Well...as for my goals...I've thrown away parts that are more than .002" out of spec. I know copper pipe and fittings are not even that close.

[boyntonstu]

Is it you goal to build as accurately as you can, or are you satisfied to live with gigantic clearances?

Well...as for my goals...I've thrown away parts that are more than .002" out of spec. I know copper pipe and fittings are not even that close.

2 mils adds what error to your cannon?