Arsenal Inc. builds an AK in 5.56 or .223. It is built in Bulgaria and the US. It is a beautiful rifle and very accurate. The 5.45x39 mags work just fine in it but I recommend getting the correct mags so if you have both calibers like I do, you can't mix them up. AS for which is better, it depends on what you want to do with them. If you get hit with a 7.62x39 you will get knocked off your feet. If you are hit with the 5.45 you will be in trouble really fast. The bullet nose folds over and the 70 grain projectile starts tumbling and going base first. The 5.45 will out shoot and out penatrate the .223 but just doesn't quite have the range. There are several Russian military videos on Youtube showing this.
Originally Posted by Ruzai
I could be a thorn and tell you skip both and get the 6.5 Grendel since it is an awesome comprimise ballistically but I wont do that since you asked specifically between the AKs.
The Ak-74 was produced to meet the needs of fighting against the m16's distance advantage and still rain hell like its big brother, the Ak-47.
But the Ak-74 shoots a different cartidge than the 5.56/223, though I believe Saiga offers a 5.56/223 AK style rifle but should not be confused with the AK-74.
The original AK-47 was chambered in 7.62x39, which is a very effective hard hitter up to approximately 250 yards. The 5.56 NATO is effective up to 750 yards, give or take a 50, depending on your particular loading.
As stated before the 5.56 NATO and 5.45 are a toss up but from what I can tell there are more choices for reloading and what not for 5.56 NATO and 223.
Ballistically speaking, if you are looking for the end all beat all AK style rifle I would try and find a Saiga .308 post-converstion. The only reason I say this is because ballistically the .308 (aka 7.62x51 NATO) is superior to both rounds iin accuracy and effective range. But of course the .308 Saiga can get heavy in a full house round like the .308.