What a Grain Is, and Why 50, 55, 62, 130 and 168 Keep Showing Up on the Box

A grain is 1/7000 of a pound. Choosing a bullet weight is mostly a matter of what your barrel twist can stabilize and what you want the bullet to do.

Bullet weight is stated in grains, a unit inherited from apothecary weights. There are 7,000 grains in a pound, so a 55-grain .223 bullet weighs about an eighth of an ounce. The number matters because it sets how fast a load can go, how well it fights the wind and whether your barrel can stabilize it.

Light bullets: speed and a flat path

In the small-bore family, 50 to 55 grains is the traditional varmint and plinking range. Fiocchi's 50-grain .223 loads are the sort of thing you find at fiocchi 223 50 grain ammo. The .222 Remington sits in the same weight class, and polymer-tip varmint loads like those at 222 polymer tip ammo are the usual choice.

A polymer tip does not change the weight. It changes the shape and the way the bullet opens. Hornady's polymer-tipped .223 loads at hornady 223 polymer tip ammo are a good example of a light bullet built to expand quickly on small game.

The 55 versus 62 question in an AR-15

M193 ball is 55 grains and M855 is 62. Twist rate decides what a barrel can stabilize: a 1:12 twist handles 55-grain bullets, while a 1:7 will also take 62 grains and heavier. Plenty of first-time AR-15 owners simply buy m193 ammo to zero a rifle, because 55 grains suits almost every twist.

The same arithmetic explains why a 5.56 page lists 55-grain and 62-grain loads side by side. The traditional practice weight is the one at 5.56 55 grain ammo.

A new rifle often starts on Winchester's white-box loads, and the 5.56 version is at winchester 5.56x45 ammo for sale. Its .223 sibling, at winchester 223 ammo for sale, is the one to use if your barrel is marked only .223 Remington.

Heavier bullets: wind and range

The .308 usually runs from 150 to 180 grains, with 150 the classic deer weight and 168 the match favorite. All-copper bullets such as Barnes' are longer for their weight than lead-core ones, because copper is less dense than lead, so shooters often step down a weight. The Barnes .308 loads are at barnes 308 ammo.

The .260 Remington shows the trend in 6.5 millimeters, where 130-grain loads such as those behind 260 remington 130 grain ammo are typical.

At the light end again, the 5.45x39 runs from roughly 53 to 65 grains. Hornady's Black line, aimed at modern sporting rifles, loads a 60-grain V-MAX, which is the idea behind hornady black 5.45x39 ammo.

Bullet weights and ballistics vary by maker and lot. Check the rifle's twist rate before choosing heavier bullets, and confirm current stock and state shipping restrictions before ordering.