Two Rivers Arms just finished a batch of Zastava M21's. These are their most recent 5.56x45 AK's. TRA made the receivers themselves. Not only did they match the receiver serial numbers to the kits, but they also matched the receiver model numbers to the kit's model number that shows on the trunnion. They had the barrels custom turned to the correct profile and chrome lined just like the originals. The kits were from various customers, but most all came from Bowman Arms originally. They kept the original blued finish on most of the parts. There are three versions of the M21. The M21A has a 18.1" barrel. The M21S has a 14.8" barrel. The M21 (what Zastava calls a "submachinegun" even though it's chambered in 5.56x45) has an 11.4" barrel. TRA extended the barrels a bit and permanently attached the muzzle brake to avoid the NFA for the M21A's.

Here was my kit before:


And here they are now: