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Reading the Box: What the Name, the Weight, the Bullet Code and the Headstamp Tell You
A box of rifle ammunition prints a lot in small type. Four things matter: the cartridge name, the bullet weight, the bullet code and the headstamp on the case. Read those and you can usually tell what the round is for.
The cartridge name
The name tells you whether the round fits your rifle. .308 Winchester is the commercial name and 7.62x51mm NATO the military one. .223 Remington and 5.56x45mm NATO are the same pairing in the smaller family. A box marked 5.45x39, as at 5.45x39 ammo, is a separate Soviet-designed cartridge.
Brand ranges are labeled in the commercial form. Federal's .308 loads, at federal 308 ammo, say .308 Win on the box.
The weight and the bullet code
The weight is in grains and the letters after it describe the bullet. FMJ is full metal jacket, SP is soft point, BTHP is boat-tail hollow point, and a name such as V-MAX or SST marks a polymer tip. Frangible .223 is commonly 55 grains, like the loads at frangible 223 55 grain ammo, yet it behaves differently from 55-grain ball.
Weight also tells you what a load is for. The 62-grain bullet is the NATO weight, and loads in that weight are part of the range at 5.56 62 grain ammo. Subsonic .308 is typically around 200 grains, as at subsonic 308 200 grain ammo, because a heavy bullet is what it takes to stay under the speed of sound.
A polymer tip on a .308, as in Hornady's loads at hornady 308 polymer tip ammo, signals a hunting or long-range design.
The headstamp
The headstamp is the marking on the base of the case. It names the maker and the cartridge, and ammunition made to the NATO standard also carries the NATO mark, a cross inside a circle. Military-pattern 5.56, such as the green tip at m855 green tip 5.56x45 ammo for sale, is often sold with markings that refer to its specification. The same goes for the Winchester M193 load at winchester m193 ammo. Read the headstamp and the box to see which specification a particular load is actually made to.
Old cartridges and familiar ones
Older cartridges print the same facts, but the names can mislead. The .405 Winchester, dating to 1904, uses a .412-inch bullet and has nothing to do with the .45-70 of the same era. The loads are at 405 winchester ammo for sale. Remington's .308 loads, at remington 308 ammunition, follow the modern convention: cartridge name first, then the grain weight and a bullet code.
Markings vary by maker and lot. When the box and the headstamp disagree, stop and check before you load, and confirm current stock and state shipping restrictions before ordering.
