Quick Tip: 5.45x39mm & 5.56x45mm NATO - What's the Diff?

Brownells Firearm Support Technician Caleb Savant briefly returns to the old days of the Cold War to talk about two competing military rifle cartridges: NATO's 5.56x45mm, the standard M16 / AR-15 round, and the Warsaw Pact's answer to it, the 5.45x39mm, originally introduced in 1974 in the AK-74 rifle. The Soviet 5.45x39 has a 60 grain bullet that exits the barrel going about 2,800 fps. The standard 5.56 NATO XM855 round has a 62 grain bullet that moves at approximately 3,150 fps - so a tiny bit more bullet mass and a lot more velocity. With a 100 yard zero, you'll see a drop of about 14" from the 5.45x39 at 300 yards, while the 5.56 will drop about 9" (the benefits of that extra velocity!). The 5.45x39's long bullet tends to tumble when it penetrates soft tissue, leading to substantial wound damage; the 5.56x45 tends to penetrate through and through. So which cartridge is better? Caleb's leaving that up to you. Tell us which round YOU prefer in the comments below.

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