Interesting…
The Ballistics FX pack by Cubit Studios has something similar to what you’re after, though it uses a single sound. It runs from mouse-clicks and not a Tick so isn’t frame-dependent. No single fire or burst modes though (you could add them), and the sound plays in full rather than being split into head and tail.
Tbh, this is something I’ve been meaning to look into more as well 
Single shot and burst fire are easy because you can set up the Sound Cue to only play one sound (using the Switch node in the Cue) or use the Concatenator node in the Sound Cue to play several sounds in a row.
The tricky part is full auto. If you want to use discrete head/tail assets I’ve found you can end up with clipped audio or some artefacts - but it is over a year since I looked at this and I know more now. You could use the Get Sound > Duration (Sound Base Reference) which will get the longest length of the Sound Cue - but this won’t be effective if you have several sounds in the Cue that aren’t exactly the same length.
Epic’s Shooter demo uses a looping sound for the weapon but I can’t see any of the logic for the weapon audio - not sure if it was written in C++ but the BPs are empty.
I’ll look into this though! 
If I can figure out a solution I’ll post a video up next week 