Grains (unit) ?

[Stoof]

So what is the deal with firearms and arrows using this unit which as I understand is a measurement of mass but in this case equals a weight? anyone know the history as to why this was adopted for projectiles?
Thanks.

[RogueSamurai]

An excellent question. I don't have a real answer to it though, hopefully someone here will.

[BrianL]

pennyweight is too long, and a scruple just sounds wierd. so 437.5 gr to the oz.

[Cajun Blake]

this might help ... http://en.wikipedia.org/wiki/Grain_(unit)

[Lokmdwn]

when you are talking bullets and powder: 7,000 grains = 1 pound,

Not sure how that equates to arrows, never really thought about it

[Stoof]

this might help ... http://en.wikipedia.org/wiki/Grain_(unit)

I have been looking around before I asked and read that but I am still trying to wrap my head around the concept.

Simple answer: Mass is a measurement of the amount of matter something contains, while Weight is the measurement of the pull of gravity on an object.

So how does this apply to the measurement of projectiles. Is the simple answer: Thats how its always been done.
Grams seems just as easy of a way to measure the amount of powder for a charge as does grains.

[Stoof]

OK, so I think I got it. Now mind you I am no physicist.
So technically you could have 2 different bullets. Lets say 30 06 and .308. The size of the bullets are different in diameter and total surface area but both could be 165 grains. therefore the material in the smaller would be more dense or heavier than the material in the other larger one. meaning that the best way to stay on standard with varying rounds would be to measure in grains.
Does that make any sense?????

[Lokmdwn]

OK, so I think I got it. Now mind you I am no physicist.
So technically you could have 2 different bullets. Lets say 30 06 and .308. The size of the bullets are different in diameter and total surface area but both could be 165 grains. therefore the material in the smaller would be more dense or heavier than the material in the other larger one. meaning that the best way to stay on standard with varying rounds would be to measure in grains.
Does that make any sense?????

I think so. The material the bullet is made from varies but gravity on the weight stays the same. without a standard measurement we would not have standard ballistic charts. That's my $.02 anyway. (Rednek logic)

[Phillip Fields]

OK, so I think I got it. Now mind you I am no physicist.
So technically you could have 2 different bullets. Lets say 30 06 and .308. The size of the bullets are different in diameter and total surface area but both could be 165 grains. therefore the material in the smaller would be more dense or heavier than the material in the other larger one. meaning that the best way to stay on standard with varying rounds would be to measure in grains.
Does that make any sense?????

No, the 30 06 and the .308 use the same diameter bullet (.308). The density will not change from bullet to bullet assuming each bullet uses the same material in construction. A 150 grain .270 bullet and a 150 grain .308 bullet (assuming same construction) will have the same density but the .270 would be longer.

The grain is the base unit of the English system of weight. The gram is the base unit of the French system. They are both measurements of mass, but the gram is metric. I suspect that the reason we use grains is because when we began to develope ballistics, the English language was the most widespread language. To further complicate matters another old unit of mass, the dram, was used, particularly in shotgun shells.

[Stoof]

No, the 30 06 and the .308 use the same diameter bullet (.308). The density will not change from bullet to bullet assuming each bullet uses the same material in construction. A 150 grain .270 bullet and a 150 grain .308 bullet (assuming same construction) will have the same density but the .270 would be longer.

The grain is the base unit of the English system of weight. The gram is the base unit of the French system. They are both measurements of mass, but the gram is metric. I suspect that the reason we use grains is because when we began to develope ballistics, the English language was the most widespread language. To further complicate matters another old unit of mass, the dram, was used, particularly in shotgun shells.

Just when I thought I had it all figured out. I do tend to over think things sometimes.
Your explanation makes sense.
Thanks.