Okay how about the following?Using parts for repair would be extremely annoying.
I would have to carry 3 or 4 different types of parts to repair my equipment in the field. During the horde I use 3 different types of firearms. At least 2 of them I have to repair several times during the horde.
We rework the repair kit into a pseudo-container. You can use if from the inventory and it opens up a menu where you can put in weapon parts to fill it. Each repair with it consumes some items from it, fixing your issue of not being able to carry that much mats while also still making players repair with parts and raw materials.