Some of the weapon drops seem weird for the Coil, personally I had a rough go of getting the Optative hand cannon to drop for me the first time. Have you gotten the hidden chests in the Starcrossed mission? I believe there's a chance for red-borders to drop from them.
English
-
Haven't touched Starcrossed since I first completed it, but it shouldn't be this hard to get a weapon to drop.
-
I wasn't trying to justify or dispute that, only offering a suggestion on how to get it.