You are standing in your local sporting goods store, staring at a wall of ammunition. You find the caliber you are looking for and toss a few boxes into your cart. Did you stop to consider the different grain options available? Grain can make a big difference in how your ammo performs, so if you are just guessing, you are not doing yourself any favors.
When referring to ammo, grain refers to the weight of the bullet, or projectile. A grain is one seven thousandth (1/7000) of a pound. Cartridges of the same caliber can have many different grain options. In general, heavier bullets (higher grain) fly slower than lighter grain bullets.
So, we are going to look at what grain means and the impact it can have on the performance of your round. We will also touch on a few basics of cartridge builds.
Basic Components of a Cartridge
A cartridge consists of four essential components: a primer, gunpowder, casing, and lastly a bullet. The primer is the source of ignition that a hammer or pin will strike. The primer ignites the gunpowder which is inside the brass casing. At the tip of the cartridge is the bullet. This is what will actually be fired out of the gun. This projectile is what we are measuring in grains. A single grain is equal to 1/7000 of a pound.
Shotgun shell pellets are also projectiles, but are not measured in grain weight the same way bullets are. Instead, we usually refer to shotgun pellets in terms of their shot size where the lower the number, the larger the shot. So if someone is talking about grains and shotguns in the same sentence, it is safe to say they don’t know what they are talking about.
How Grain Affects Power Factor
Power factor is a way to measure the power and speed of the ammunition you shoot. If you ever shoot in a competition, you will need the right power factor to be allowed to compete. You calculate the power factor by multiplying the speed of a bullet in feet per second with its weight in grains, and then dividing by 1000.
For example, a standard 115 grain 9mm bullet flying at 1180 feet per second has a 135.7 power factor. Where a 40 Smith & Wesson moving at 1000 feet per second and weighing 180 grains, has a 180 power factor and would generally be considered to be more powerful than the former 9mm round.
A 150 grain bullet and 165 grain bullet in the same cartridge will only have the same power factor if you changed the amount of powder in the 165 grain bullet’s casing and made it faster. This is not an adjustment major manufacturers make because it isn’t always safe to do, therefore different grain weight bullets produce different ballistics data.
Light vs. Heavy Grain Characteristics
If you go with a lighter grain bullet, you will get more speed and distance out of your projectile. If someone handed you a one pound rock and a five pound rock, the one pound rock should get thrown further by the same amount of power.
On the opposite end of the scale, a heavier bullet is more effective in packing a punch. Plus, when you talk about hunting, a large bullet will make a larger wound channel and generally cause more damage. Although speed is still fairly important. You shouldn’t notice any additional recoil with larger grain rounds either.
Grain by Grain Comparison
To see the difference such a small amount of weight can make, let’s look at some basic numbers from a common .243 Winchester. These numbers show the difference between two Remington Core Lokt rounds. The only difference is that one is 95 grains while the other weighs 100 grains. Here, speed is measured in feet per second (fps).
| 95 Grains | 100 Grains | |
|---|---|---|
| Muzzle | 3140 fps | 2960 fps |
| 100 yards | 2866 fps | 2697 fps |
| 200 yards | 2608 fps | 2449 fps |
| 300 yards | 2364 fps | 2215 fps |
| 400 yards | 2134 fps | 1994 fps |
| 500 yards | 1916 fps | 1786 fps |
The difference in fps between the two sizes ranges between five and nine percent at each distance. This seems significant considering the 5 grains are equivalent to about one-hundredth of an ounce! The difference between these two cartridges is that the 95 grain bullet is going to fly farther, and therefore farther; it also has more kinetic energy than the 100 grain bullet at every interval.
For an example with a greater grain difference, the table below shows the difference in two Winchester Ballistic Silvertips chambered in 30-06 Springfield.
| 150 Grains | 180 Grains | |
|---|---|---|
| Muzzle | 2900 fps | 2750 fps |
| 100 yards | 2687 fps | 2572 fps |
| 200 yards | 2483 fps | 2402 fps |
| 300 yards | 2269 fps | 2237 fps |
| 400 yards | 2103 fps | 2080 fps |
| 500 yards | 1926 fps | 1928 fps |
If you are paying close attention, you will notice that the heavier round actually produces more kinetic energy than the lighter round; which is the opposite of the last example. This is because the heavier round is still able to achieve respectable speeds, and its significant 30 grain difference gives it more energy overall.
That is why you have to compare cartridges so closely. When we changed caliber in the last two examples, everything changed. So you don’t know for sure which grain is the most powerful until you do the math. Don’t worry, there are online calculators for that.
Although, you shouldn’t just pick the one that is the most powerful. Some rifles prefer a certain grain, and you don’t know that until you shoot it. During your break in period with your new rifle, shoot a few different grains. Your MOA can be significantly different between grains, even from the same brand. Even rifles of the same model and year can prefer different grains.
Grain Weights for Different Purposes
What you are going to use your ammo for will help determine whether you should be reaching for a lighter grain or heavier grain bullet at the sporting goods store. Not every round is created equal.
Hunting and Self-Defense
For hunting and self-defense purposes, heavy grain bullets tend to be the better option. They do a better job of delivering a punch to their target, and creating larger wound channels. They hit with more momentum and carry a higher power factor. This is especially useful in self-defense situations that often happen at close range where you don’t need to worry about bullet drop.
The one exception for hunters is if you are hunting at extremely long ranges. In that case, the speed and trajectory of lighter bullets might be what you want purely because they usually have a flatter trajectory, which makes it easier to hit longer shots.
Long Range and Marksmanship
When shooting at long-range targets, let’s say over 400 yards, a lot of the heavy bullet characteristics lose their usefulness. At long range, you normally aren’t taking shots in quick succession. You have more time to take a breath, refocus, and take another shot.
If marksmanship and shooting sports are your main purpose, then lighter bullets make sense because of their flatter trajectory. You also don’t have the need to pack a lot of punch when the holes you are punching are in paper.
How Bullet Design Affects Grain
There are many bullet design variables like their shape and material that will affect a bullet’s weight. If you simply Google “different bullet shapes” the names can be confusing. Some, like the flat base, are named for the shape of the back end of the bullet. This is called the heel of the bullet. Others, like a round nose or hollow point, find their distinguishing features at the tip of the bullet.
The most common bullet shape is the flat base. On a flat base projectile, the heel of the bullet is the same diameter as the bullet’s midsection. It does not taper down as a boat tail bullet does. Boat Tail bullets are made to promote more aerodynamic bullet flight, and therefore are popular with long-distance shooters. Flat base bullets are the most common type and are the easiest for manufacturers to produce.
The most common tip designs include full metal jackets, soft points, round noses, and hollow points. A full metal jacket bullet has a lead bullet that is completely encased in a copper jacket. A soft point means there is a small tip of exposed lead sticking out of the metal bullet case.
Round nose and hollow points are very common in handgun rounds. Round nose bullets are typically made of lead so they are easy and inexpensive to make. When you hear the word “bullet”, the picture that comes to many minds is the round nose design.
You can easily see how these different designs and shapes can make a bullet weigh different amounts. When you start adding in other materials like lead, copper, or plastic that weigh different amounts, you can even start getting different grain bullets that are more or less the same shape.
The majority of bullets are made of lead, which is where the majority of your grain weight comes from. A combination of metals, mainly copper and tin, are used to create most bullet jackets. A jacket is usually required to keep lead bullets from ripping apart mid flight. Some bullets may include inserts made of plastic to improve terminal ballistics (AKA reduce drag) without adding much weight.
Does Grain Weight Affect the Price of Rounds?
Another misconception about ammunition and grains is that lighter grains are cheaper. That is just not the case. Scouring websites will quickly show that if the only difference is grain weight, the price is usually the same. The components and materials that different manufacturers use to construct their rounds will have a greater influence on the price of a round.
Usually you will pay more for more intricate designs. Full metal jackets are the simplest to manufacture, and are usually the cheapest. Jacketed hollow point rounds are a little more complex, and therefore a little more expensive. Self defense pistol rounds have a ton of engineering poured into them, and you definitely pay for that.
A Parting Shot
Bullet grain weights can be a source of confusion for newer shooters. Understand that grains refer to the weight of the projectile and that different cartridges of the same caliber can have different bullet weights. Those different weights will make the round perform slightly differently from one another. Bullet weights are a pivotal part of ballistic charts, and when you understand how to use those, you can make very informed decisions while you are standing in the ammo aisle.
