You will just need to recalc the forward vector, using the end point and the weapon location.
Please forgive the formatting, wanted to make it obvious what needs to be added 
Edit: Ooops… also reset Forward Vector to the normalised value, before scaling it and setting Forward.
Edit2: Double Oops, you don’t have that, but create a local and use that instead of the Get Player Camera Manager → Get Actor Forward Vector in the middle sequence path.