Hey Claviateur!
What you need is a cone trace which there is a whole different thread for that: Cone Trace - Programming & Scripting / Blueprint - Epic Developer Community Forums (unrealengine.com).
However, I recommend multiple line tracing. You can cast multiple random lines in random directions with a maximum deviation angle from your gun forward vector, imitating a cone. If you are having trouble with random line directions, you can pick your direction as simply as done in this:
Which is a cone that is seen as a circle from the perspective of your gun with the lines as the deviation of your line directions from the forward vector. You can also change the number of lines as your project requirements desire.
Now you don’t have to reduce the impulse as the hit distance increases since each line trace could add its constant impulse and the closer the object is, the more lines hit it and the more impulse it catches. Also, now you can hit multiple objects with one shot. If you are trying to be very realistic, yes, you can also take the hit distance of each line into the calculation of the impulse it is adding.
If had any issues with making the blueprint, just post here and I’ll be happy to help!