This is a simple guide for farming ultra rares if you don't have enough points to 'retrieve parcels' to get the achievement.

This guide shows the ultra rare farming method as well as an overview of rare items in the first 6 waves of BREACH

• The sector used for farming is BREACH
  
• End the day by selecting the navigator and choosing end day
  
• The parcel costing 12700 is the last parcel
  
• Skip waves by deactivating the magnet after a crate hits your crate
  
  
• There is no point in saving any items in your inventory
  
• The game doesn't care / require that you keep at least one of each loot item to unlock anything
  
• The game only cares if you have found the loot items once before
  
• There are probably other better sectors to farm for items but this is one I noticed had a good amount of easy rares and really easy ultra rares
  
  
• Ultra Rares are worth 250 points
  
• Rares are worth 50 points
  
• Commons are worth 10 points

Doing wave 2 (the first 2 crates only) and wave 5 only
Wave 2 - 6 common
Wave 5 - 2 ultra rare (last crate, second to last crate from side), rare (second container)
End day

Approximate farm time calculation
10*6 (6 commons at 10 points each)
250+250+50 (2 ultra rares each 250 points, 1 rare 50 points)
610 ~ 1 minute (total of 610 points for approximately 1 minute farming)

12700 / 610 = 20.81 minutes (around 20 minutes [at ~1 minute each run] to farm the last parcel if you have 0 points)

Wave 1 - skip
Wave 2 - 1 rare, 6 easy commons, weapons locker
Wave 3 - 4 rares (one sometimes falls out of 2nd crate after 3rd crate hits)
Wave 4 - 4 rares
Wave 5 - 2 ultra rare (last crate, second to last crate from side), 1 rare (second container)
Wave 6 - 4 rare, weapons locker
End day

I included some weapons lockers but they really aren't necessary