Is it 556.45 or 223? You would think since it`s Russian / European it would be 556.45. On the other hand since it`s exported to the USA it could be 223.There is a small differnce.Some on the other boards say it`s not 100% safe to cross the two.And to tell ya the truth I am not real worried about it,I`ll be shooting 223 in mine. But it would be nice to know for sure. wolfeyes/ john horton