Two bone IK is jittering when attempting to set the location to a socket on the weapon skeleton.

[Kris]

Could be the usual one frame lag sort of issue.
Animation blueprint is being updated in one thread, the firearm and other parts of the game your getting info from are in another.

Check out the following if you haven’t already.
Its directly related to hand IK for firearms etc:

Hand IK with different grips

Hello all, I have been doing some investigation into left hand bone IK so that I can adjust the left hand of my character to fit different weapons. However I have noticed that many of the tutorials online work, but only for holding the barrel of the gun or maintaining the original idle animation. So if I were to equip a vertical grip for example, the hand could change its position to be more in line with the grip, but it does not rotate to look like it is holding the grip properly. I was wonde…