Because it’s relatively new and adds in a bunch of overhead that you dont necessarily need, since you know, the systems which work have been in place long before.
Now, if you want to study how those work and replicate them in control rig, sure, its possible. But you have to make sure you aren’t adding in extra load just becauae of using control rig too, since its obviously not required to make said systems work.
No, in theory, it is partly what it was built to do.
Except it was originally made to sync up different meshes with different extra bones to base animations of a different skeleton.
And it then got adapted to just work on the main skeleton itself. So you have to check how performant the latest iterations are…
If VB stands for virtual bones. Those too are new-ish.
The oroginal epic skeleton had extra IK bones which are useful (and used by most setups) for habdling weapons.
Nothing prevents you from adding weapon specific bones to your character so you can animate the gun properly (putting away a rifle is different than holstering a gun. Do you really heed 2 bones? No, but will it hurt to have 2? Not really, so why make things complicated when you can add in the extra bone?).
That however is a different discussion - you need those regardless of the setup to aim, which will in all likelyhood use the IK hand bones.
As far as specific tutorials, I’m not sure really. I just went with what was right for my project. There’s a billion different ways to do this even with the primitive tools, so you just have to learn how the basics work to make up your own system.
A few things you may want to work into in advance:
Hand position varies on a weapon by weapon basis. Each weapon needs to be offset to its socket on the weapon bone differently to be able to share animations.
Rifle requires 2 hands, so you need to allow weapons to define L and R offsets for each socket.
I don’t think you should use 2 sockets on the main actor, but you can add sockets to anything - and therefore adding sockets to the weapon itself could help in defining the offsets visually.
Solving the IK chains backwards you need to keep count of proper elbow pole position - adding a bone may seem like a good idea here, but what if a different rifle requires a different position?
As such, we go back to having the weapon defining elbow offsets too. This time probably using values for an offset instead
(For noncomplicated setups just put the elbows inwards to support weight as a proper shooting stance should always be. Left hand forward hand elbow points down. Trigger hand points as down as it can, limited by trigger locarion).
Running or walking with dofferent rifles requires to adjust left/right position of hands holding it based on weapon weight. Different weapons swing differently.
Different character structures - wide shoulder vs narrow - will need different IK values to move the rifle Up for wide, down for small generally, in order to possibly fit similarly.
Above all remeber that the IK setup is a suggested location.
The character will try to reach it. If your limits are correct, gripping a 2cm large AK will result in the forward hand failing to reach its location and looking OK anyway. (I’d suggest that if the target is not matematically reachable you change animations/drop the second hand, but that’s probably more of a nuance).
Last tip. Working without control rig, the fabrik solver is probably the best one to use.
Different solvers have different load on the system. Iccd is lighter for instance. Fabric means more control. And the other ones are situational at best.
Also, the location in the ABP hierarcy is likely after all animations have already occurred, like for leg IK. But the offsets should only be active when needed (done via an alpha value).