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

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 5.56×45 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 5.45×39 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 5.45×39 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.