No ARs are spawning on PC, and its been a bug for a very long time. I stream DayZ and have played over 300 hours in the last 4-5 months, I always spend my time north and on various servers. I thought this would be addressed in the new update, but it was not.
When AK74 was released, there were plenty of ARs. You'd find at least 2-3 in the North West, and at least that same amount in Tisy.
Now, not so much.
A lot of ppl have said this is due to dupers/hackers taking too many ARs out of the loot economy. Which is not fair to us players who want to use the new weapon attachments & old ones alike.