Thanks for the playthrough feedback, yes the lack of chaingun was intentional, figured it would give the level an element of 'survivability' and scrounge what you can after being captured and shipped away in a crate. That switch at the exit started a crusher in the monsters teleporting spawn boxes to allow you to get 100% kills in case someone pesky decides to not spawn in correctly. Just changed it to a walk over linedef trigger as you approach the exit, net same effect without the confusion.
Here's the update:
https://wadhosting.com/Wad/7522A897FAAA2D615770F1E562188B81691D186C