By Duane Thomas
As you approach the wonderful world of handloading, you might be asking yourself, “Why is the unit of measurement for bullet weight, and powder charge weight, called “grains”? I know I did.
Return with me now to those thrilling days of yesteryear! (In this case, ancient Mesopotamia.) The Lone Gunwriter rides again!
The term “grain” to denote a particular unit of weight originates from the use of actual grains, as from wheat or barley. “Grain” has been used as a measure of weight since at least ancient Mesopotamia. The grain was one of the smallest units of weight, and works because individual grains of wheat, or similar seeds, are relatively uniform in size and weight. Even though individual grains of wheat could vary slightly, using an average weight provided a consistent measure.
Over time, this measure was standardized. In the apothecary system, a historical system of measurement used primarily in pharmacy to weigh and measure ingredients in medications, a grain actually was the smallest unit of measurement. Though measurements of weight in ancient and medieval times were not as accurate as they are today, still the “grain” provided acceptable precision.
Today, with the metric system having taken over in modern pharmacology, a grain has been defined as exactly 64.79891 milligrams. The term “grain” has stuck around in pharmaceutical terminology, partly due to tradition and for historical continuity because it’s been long-established in medical literature, prescriptions, and drug manufacturing, though its use today is quite niche. For instance, some practitioners of homeopathic medicine may prefer to use “grains” for reasons of tradition. In modern professional pharmacology, when we do see “grains” it will generally be alongside, or converted to, metric measurements for clarity and accuracy in dosing.
Now we move into firearms usage. The use of the “grain” for measuring the weight of bullet and gunpowder charges can be traced back to at least the 16th Century, when firearms and black powder began to become more common. Black powder was traditionally measured by weight because its performance was closely tied to the amount used.
By the 19th Century, with the increasing sophistication of firearms and ammunition, the grain became a standard unit in the U.S. and Britain for measuring both bullets and powder charges. This was particularly true with the advent of more precise manufacturing and the need for consistent ammunition performance.
As firearms technology evolved, especially during the American Civil War, and with the introduction of metallic cartridges in the latter part of the 19th Century, the grain became the established unit for specifying bullet and powder charge weights. The development of smokeless powder in the late 19th Century further solidified the use of grains since precise measurements became even more crucial for performance and safety.
Historical texts and gun manuals from the 18th and 19th Centuries refer to bullets and powder charges in grains. For instance, the naming of cartridges like the .45-70 Government (where “70” refers to 70 grains of black powder) from the late 1800s shows this transition was well underway by then.
Today, the grain remains the standard unit for measuring bullet weights and powder charges in the Imperial system, especially in the United States. It’s used to define both the weight of the projectile (bullet) and the amount of propellant (gunpowder) in a cartridge.
So now you know. From actual grains of seeds, to the apothecary system, to modern pharmacology, to black powder, to smokeless powder, to what charge weight you look up in a load manual when putting together a new load recipe to assemble with your reloading machine.
