5.45 vs. 5.56: Are These Cartridges That Different?

The 5.45x39mm vs. 5.56x45mm: two historied cartridges that have battled it out on the front lines for decades. That leaves many shooting enthusiasts wondering which is better. As you continue reading, you’ll learn the differences between the two cartridges – and which one is better for your shooting needs. Let’s compare and contrast 5.45 vs. 5.56!

Overview of the 5.45x39mm and 5.56x45mm

The 5.45x39mm was developed by the Soviet Union and adopted into service in 1974 for use in the AK-74 rifle. The Soviets’ goal had been to develop a cartridge similar to NATO allies’ 5.56x45mm (but not so similar that allies could use captured stashes of Russian ammo in combat). To this end, they were successful.

The 5.56×45 was developed by FN Herstal. The nearly identical 223 Remington had been developed by Remington and Fairchild Industries for the U.S. Continental Army Command (CONARC) in 1957. The 5.56 was officially adopted by the U.S. Armed Forces in 1963, primarily for use in the M16 rifle.

Both cartridges allow soldiers to carry more ammunition into battle (relative to larger rifle cartridges, such as the 7.62x51mm NATO and 7.62x54mm), have low recoil, and offer similar ballistic performance to one another when loaded with similar bullets.

5.45 and 5.56 Pros and Cons

Ballistics Comparison: Velocity, Energy, and Bullet Drop

Note: The following information comes from ammunition manufacturers. Actual ballistics obtained with your firearm can vary considerably from those advertised. Also, ballistics can vary from lot to lot with the same brand and load type.

Recoil and Shooting Experience

Having owned several 5.56 rifles over the years, I’ve lost count of the number of times new shooters have shown surprise by how little it kicks. You can expect 5 to 6 ft-lbs of recoil energy hitting your shoulder while firing a 7-pound rifle. (That’s comparable to your buddy gently punching you.) The 5.56 is one of my favorite cartridges for shooting targets within 200 yards because it’s accurate, and its low recoil means I can spend hours at the range without earning a sore shoulder.

The 5.45×39 delivers even lighter recoil. You can expect 2.5 ft-lbs of energy pushing against your shoulder while firing an AK-74. That’s hardly noticeable. Its gentle kick allows quicker follow-up shots and better accuracy. The 5.45 is known for its high velocity and relatively flat trajectory, which both contribute to its generous effective range.

Accuracy and Effective Range

Both cartridges are highly accurate in the hands of a capable shooter. The 5.45×39 tends to have an effective range of up to 500 yards, while the 5.56 boasts an effective range out to 600.

Penetration and Terminal Ballistics

Penetration depth and terminal ballistics are highly dependent on bullet selection. Most 5.45x39mm bullets are designed to tumble upon impact, which can establish a large wound cavity. On the other hand, most 5.56x45mm bullets are designed to fragment upon impact, which can inflict more soft tissue damage. The 5.56 has a slight advantage in stopping power and wounding potential, whereas the 5.45 offers superior penetration against light barriers.

Read the full comparison here: https://ammo.com/comparison/545-vs-556

Source: https://freedombunker.com/2025/11/10/545-vs-556/