There's no difference in the rifling. The differences between 5.56 NATO and .223 Remington are all in the chamber dimensions.

Bottleneck cartridges usually need two reamers. Unlike straight-wall pistol cartridges, rifle cartridges require opening up the chamber to a much larger diameter than the bore. A rough reamer is used to aggressively remove material to get the chamber near the correct size and then a finish reamer is used lightly cut the chamber to the final dimensions. The same rough reamer is often used for both .223 Rem and 5.56 NATO (and .223 Wylde). The fini…

u/pearljamz · 2022-04-19 23:13:43 UTC · score 113

These are drop-in followers for AK74 magazines. They convert 5.45x39 mags to .223/5.56 so you can larp around with your NATO AK and still look as cool as your 5.45 buddies. I’ve tested them successfully in plum, bakelite, commercial Bulgarian, and AK-12 mags. They load up to 32 rounds and can utilize the …