OK this is my idea for C4, dont remove it and dont make it harder to get but make it more dangerous to the user.
When your making C4 there is a chance that it will explode like a 40-50% chance.
If your running with C4 it can explode again 40-50% chance.
there could be different types of C4, Ones that only can come in air drops or spawns, these are super rare but dont randomly explode. Next the ones that you can craft but these can explode while crafting them or when running around with it, they also have bad timers so like when your putting the C4 on a door,wall,etc the timer will malfunction and instead of going of in 15 seconds it explodes right away there would be like a 20-30% chance of this.
Sorry if this is hard to understand, please ask me questions.