The one I fondled belongs to a mate of mine and he has said it runs flawlessly on whatever cartridges he feeds it and will take genuine Saiga mags with a bit of a file on the back of the mag, I think this is due the the Armtac having a straight insert magwell whereas the Russian Saiga mags "rock and lock" like a traditional AK.
I will be trying on the range over Christmas so will update on how it shoots but if first impressions are anything to go by I can see one of these finding it's way into the cabinet at some point , especially at the price they are compared to a Russian Saiga or Vepr-12.

