7.62mm or 5.56?

[thelurkinghorror]

@swampspruce

As far as NATO rounds I would prefer the 7.62 overall as it has slightly better penetration characteristics and range. I was trained on the C7 and C1 (M16 and FN) when I was in the military and if it were me alone, I’d pick the FN every time. As noted above, there are a LOT of variables other than caliber to consider in your original question. YMMV…

The FN FAL/C1 uses 7.62x51mm which is different from the 7.62x39mm mentioned by the OP. The 7.62 NATO is indisputably more powerful than either of the intermediate rounds but it is no longer used for rank-and-file troops mainly because they are bigger and heavier.

Left to right in this image:

1. 7.62x51mm aka* .308 - used by M-14, newer bolt action rifles. Roughly comparable to the mostly bolt action 7.62x54R. Replaced .30-06 (similar performance) and was replaced by:
2. 5.56x45mm NATO aka* .223 - used by M-16/M-4/AR-15
3. 5.45x39mm - used by AK-74 etc.
4. 7.62x39mm - used by AK-47 etc.

The bullet weight of 7.62x39 is about 2x the weight of 5.56 and .308 is about 23% more than 7.62x39, but with lots more powder behind it.

The Soviets intended 5.45 to replace the 7.62x39, and it has done so in the now Russian military. The larger cartridge is still very/more common in civilian markets and the “third world.”

*not exactly the same but often interchangeable. Specifically it is okay to shoot .223 in a 5.56 marked rifle, or 7.62x51 in a .308 marked; the opposite may not be okay.