If you’ve picked up your ammunition at your local sporting goods or gun store, you’ve likely notice the number on the side followed by “gr,” “gn,” or “grains.” So what does grain mean when we talk about ammunition? Grains are a unit of weight measurement, and on a box of ammunition the grains describe the weight of the projectile. Therefore, the higher the grain the heavier the bullet.
20g weight on a digital scale converted to measure in gr
Because grains describe weight, there are other parts of ammunition that utilize this unit of measurement. The powder charge — the smokeless powder inside the casing — is also measured in grains.
However, when you are buying a box of ammunition the grains printed on the side refer to the bullet weight and not the powder charge. Grains are used to measure weight, and as such, can be converted to grams, pounds (lbs.), or any other unit of weight measurement. However, it is usually reserved for small weights and I have only ever experienced something measured in grains when discussing ammo.
Is Higher Grain Ammo Better?
Higher grain ammunition — or heavier bullets — can be a good thing depending on your needs. In my recent firearm instructor course, I spoke with a competition 3 gun shooter. He finds higher grain ammo better for knocking down steel targets.
If you need to generate more “stopping power” then a heavier grain bullet is going to be better. For instance, if two bullets with different grains exit the muzzle with identical velocity the heavier bullet will generate more momentum.
Contrarily, if you need to maximize accuracy over distance then a smaller grain bullet may be beneficial. If two cartridges are loaded with the same charge, the lighter bullet will achieve greater velocity which translates to a longer distance.
Does Higher Grain Ammo Have More Powder?
Powder charge for a 115gr 9mm bullet before loading
If a higher grain bullet is heavier, then does it require a greater powder charge? Higher grain ammo does not necessarily have a larger powder charge. In fact, sometimes a heavier bullet requires a smaller powder charge to achieve the same velocity.
The data I’m about to cite comes from the Hornady Handbook of Cartridge Reloading and is not my own. However, a 115gr FMJ RN bullet requires 7.4 grains of Accurate No.7 powder. But a 124gr FMJ RN bullet requires only 7.2 grains of Accurate No.7 powder to achieve the same velocity.
Does Higher Grain Ammo Cause More Recoil?
The long and short answer to the question of whether a heavier bullet causes more recoil is, it depends. Generally speaking higher grain ammo requires more energy to move. Therefore, the recoil will be greater for a heavier bullet if all other things are equal.
However, there are a number of factors that impact recoil. If for instance the exit velocity is lowered, then the energy transferred to the gun will be less. Ultimately, this leads to less kick when firing the gun.
Hopefully this information has been beneficial to you. The key takeaway from this article is that the grains on the side of the ammo box describe the bullet weight and not the powder charge. If you know someone who might benefit from this information, please feel free to like and share, or leave a comment if you have a different opinion.