It's probably just you seeing things, alongside confirmation bias, negativity bias, etc etc.

The swapping behaviour of a Hireling works on a short timer. When the timer finishes, they make a decision. Their decision on whether or not to swap checks if an enemy is in melee range (I think the range for that is 3 if memory serves) and if the Hireling is holding a ranged weapon. If the answers to both are the same, they swap. Then, it starts the timer again and repeats.

I see, thanks for responding, it was probably just me. Played tinker that playthrough and decked out the guns, probably added an attachment somewhere. Guess my biggest problem is when i gave my hirelings massive/huge weapons, and then they keep switching back and forth. Never really looked into the ai of the hirelings so maybe this just happens normally. Have a nice day.