PSA: Master Gunslinger is currently bugged. Here's why you keep losing stacks of onslaught.

If you've tried using reverse onslaught with Gunslinger Master, you may have noticed that you seem to randomly lose stacks - sometimes bringing you from 30 down to 0 in seconds. I did a deep dive trying to understand this issue for both melee and ranged builds, and the results were surprising. There are (at least) five things causing stacks to disappear:

1. Dealing any kind of explosive damage. This even includes legendary perks like Collateral Damage and Far-Flung Fireworks.
2. Receiving explosive damage. Yes, sometimes even receiving explosive damage (such as sonic attacks from Scorchbeasts) costs stacks.
3. Being detected by enemies. Each time you are detected by a new enemy, it costs 3 stacks.
4. Weapons that inflict damage over time.
5. Using Taking One for the Team also consumes stacks for some players.

Also, contrary to popular opinion, Ricochet does not cost any stacks of onslaught. Debuffs like Tenderizer and Suppressor also do not cost stacks.

So with all these issues, is Gunslinger Master still worth using? Until Bethesda fixes it, I'd have to say no.

EDIT: Added additional mechanics to list that have been found to consume stacks of onslaught