Tier 5 (Fal, svd, vss, asval, m4a1...) loot is not respawning at the Radunin toxic zone. I already looted it 5 times and found only tier 4 loot. At the same server I also looted the airfield toxic zone and found tier 5 loot, so it's probably an area problem.

I also notice that the Shipwreck, Pavlovo and Airstrip toxic zones are smaller than Radunin, taking only 2 and a half filters to loot, and Radunin taking up to 4 and a half filters. Maybe having a so large toxic zone is making the tier 5 loot spawn on hidden areas inside of it.