Where did you get the epic armour mod, I'm 18 in tech and only have the common one
If you can craft the common one make sure you have the follow Perks added to the Tech Ability "crafting" tree -
Efficient Upgrade - it has a 10% chance of upgrading your crafted item - This is what allows a common Armadillo to be upgraded at random during crafting. However it's advisable to also get -
True Craftsman (Craft Rare) &
Grease Monkey (craft Epic) as well to get a Rare/Epic upgrade whilst crafting. So if you craft a common Armadillo say 30-40 times you'll get a range of Epic, Rare, Uncommon and Common Armadillos.
I also run
Ex Nihilo (20% chance of a free crafting) and bunch of other Stuff, my crafting Tech tree is virtually all filled in. It does kind of break the game a little TBF being able to craft upgraded items for "free" as you can then disassemble the upgraded items so one common Armadillo costs say 6 common and 4 uncommon but it could get you 1 epic which can be disassembled for 4 common, 6 uncommon, 4 rare, 6 rare upgrades, 3 epic, 1 epic upgrades - so you can see if you crafted 200 common, you'll get a whole heap of stuff extra during disassembly - like I said, it's a bit game breaking so I rarely use it like that and prefer to play the game as meant, using Gun/Clothes stores, disassembling captured enemy weapons/clothes etc.
Think a lot of weapons have quirks like that - I was having some oddities with precision rifles in some cases until I realised they were consistent but not where the aim point supposedly was with some sights.
In the Gameplay settings, if you select Weapons Sway to "With Camera" rather than "With Weapon" it keeps the gun sights always in the centre of the screen, where as with Sway with Weapon the gun sights wander all over the place giving you multiple "sights/crosshairs" to look at (players POV crosshair, gun crosshair all point at different places etc).