I've been having this problem since Beta, and I've seen quite a few posts about this issue before but no actual solution.
Whenever a bot or a player dies and drop their weapons, their gun sound goes on, sometimes for a couple of minutes, and sometimes it's constant until the end of the round. It's almost impossible to hear anything else going on in the game (or on Discord/TS for that matter) during that.
It happens to me and some of my teammates in all maps, in random locations, both on Co-op and Versus modes, matchmaking and community servers alike.
It seem to got worse after the recent update. While before that I usually got this bug once every couple of rounds, or sometimes not even at all, since the last update I've had it on every single round.
The only workaround I've found for it is to change the in-game audio settings when it happens (changing the volume up or down, even just a bit). It works most of the time, but it obviously isn't an actual solution (especially not while on a PVP match when I'm capturing an objective as the last man standing...).
I've also read that finding the noisy weapon and picking it up could solve it as well -- but it's so loud and irritating that I doubt I'll run around the maps looking for it.
Any suggestions will be appreciated. If there's further information needed to help fix it -- I'll gladly give it.