Today, I talk about grains. As always, I'm so far from being an expert it's not even funny. But writing these things down helps me assemble them in my brain and might help other new gunnies reading this.
So, grains still confuses me after lots of reading. I think this is because the term is used to refer to BOTH the weight of the projectile (bullet) AND the weight of the powder in the round.
A grain is a unit of measurement, with 437.5 grains equaling one ounce or 64.79891 milligrams. (This where I start bemoaning our use of the imperial system rather than the much easier to understand metric system.)
History of the term grain is a bit ambiguous, but seems to come from England:
"where it referred to the weight of a barleycorn. This made the English grain larger than the corresponding grain units of France and other nations of the Continent, because those units were based on the weight of the smaller wheat grain."
When your ammo box indicates grains, it is only the weight of the bullet, not the powder load. Different brands will use different amounts of powder, but this may not be readily available on the box. Hence why different brands of ammunition with the same bullet weight (grains) shoot differently.
So, how does bullet weight affect my shooting?
Light bullets move faster (given equal powder) and have a flatter trajectory. This should make them easier to aim, especially at close range. Because they are lighter, they will have less impact force at longer distances.
Heavier bullets will have more resistance and thus more arc to their trajectory, thus needing more compensation in aim point at longer distances. However, thir weight allows them to retain speed and power at longer distances.
(For those archers out there, this is similar to differences seen with different arrow weights, lengths, and points)
As to the grains of powder, more is not always better. Increasing the powder results in more force applied to the bullet upon firing. This results in more velocity to the bullet, but can also cause more recoil. Most powder loads will be similar across brands from what I understand. The exception is in +P loads that will have havier powder loads.
That's the basics. I tried reading more details, but I ended up more confused than when I started. Maybe in the future... I know lots of you out there are more familiar with this than I. So, please correct me if I'm off somewhere or missing some crucial point in this explanation of grains.
Oh the joys of ballistics...good times. This is my current obsession. It is confusing. There are so many contradictions and different ways to name the same type bullet and yet even if they technically mean the same thing, there can be differences. It's still fun though.
ReplyDeleteThe way I remember it is 7,000 grains to the pound. It's just another unit of measure. My recipe for .45ACP is a 200 grain hollowpoint loaded over 7.0 grains of Unique powder. This is a mild +P load that yields just under 1,000 feet per second out of a 5" barreled 1911 pistol. With this recipe I can load 1,000 rounds with a single pound of powder.
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