Hey, I have a character set up using collision capsule components attached to all the relevant parent sockets to make a somewhat accurate hitbox for weapons etc.
I couldn’t find anything on this topic but are the default collision capsules very accurate or would I be better off making wireframe spheres and capsules in blender with more subdivisions but still far less vertices than something like the starter sphere mesh in UE??
Are you finding them inaccurate? Afaik, there are special optimisations for primitives on the lower level, closer to the metal; or so I read once upon a time.
No I’m not having issues with them but I’ve seen the capsules and spheres used in other games and they have significantly more subdivisions than the standard UE ones. So If i was going to do something like that I’d just rather do it now and not have to worry about it later
Again I couldn’t find much of anything regarding hitboxes and the collision components.
The primitives do not use triangles / polys to calculate collision, it’s just a bunch of math - a box, a sphere and a capsule are easy. Other shapes are not and only then we must fall back on Simple Collision (or multiple primitives). In many cases, Simple Collision is still a bunch of primitives + convex volume.
Were you to add your own custom colliders, you would, most likely, make it less accurate and less performant. Someone please do correct me if I am mistaken. 
Either use default unreal capsule/sphere/box (or anything else it offers) collision, or use complex as simple if you want to be mesh accurate.
I sense OP is swinging swords / spraying bullets at mobile targets. So complex collision ain’t gonna cut it. One way or another, they wanted it more efficient, not less.
But yeah, stick to the native primitive collider where you can.
There could be only one enemy in their game, than it would be ok to use complex.
Complex collision cannot be mobile. You can’t move or simulate it.
Unreal should fix that.
Maybe they have a static enemy.
the intention is for there to be quite a few enemies and yes mostly swords with some projectiles.
I’m perfectly happy to stick with the default collision components, just wanted to know of other potential implementations 
If complex (custom) collision is not mobile, you couldn’t use them anyway.