ZDoom

I was working on a replica of the heavy machine gun from Soldier of Fortune for my Zandronum mod (also works on GZDoom) but there's a issue going on with the sound. I want the firing sound to be sequenced exact like in SoF (the shoot sound should be overlapped not be resetted or limited). So I use this: It kinda worked on Zandronum but when I use the footsteps mod, it interferes with the shooting sounds. Even without the footstep sounds mod, it sometimes doesn't work. But when I use this in the most recent GZDoom version, it doesn't work at all, even without footsteps. I tried this method: But this didn't work either. Is this a bug or did I something wrong?

The footsteps mod I mentioned can be found here. (I used the Zandronum version)
The gun can be grabbed here. Just open it with GZDoom, select DOOM or DOOM II, start a level and type "give heavymg" via console.

I tested the weapon alone with GZDoom 3.3.2. The flag seems to behave as expected: while the firing sound is playing, no other instances of itself (those with CHAN_NOSTOP set) play on that channel, and thus the sound plays fully without being overridden or interrupted by those instances.

Is there a way to bypass it?