The evolution of the 1;7 twist rate on the M4

[Quiet]

The South Koreans (Daewoo Precision Industries/SNT Motiv) went with a 1 in 7.3" twist on their 12" to 18.3" barrel length K-2 rifle series for use with their SS109/M855 ammo.
They used the 1 in 12 twist in their K-1 series of "submachine guns" and for all their rifles made for the civilian market.

That's what the online sources say about the military guns. That doesn't mean the retail guns were the same. I could swear my manual said my AR-100 that I bought brand new in 1989 said it was 1 in 12.

My recollection is the early imports were 1/12 and at some point changed to 1/7. The post ban DR?s are all 1/12.

The 1 in 12" twist was standard for rifles made for the civilian market.

Some K2 style rifles had 1 in 7" twist because that is what the importer requested, however they want back to the 1 in 12" twist after the US ban on the importation of military/machine gun barrels.