Bolt staff final charge level - does it do anything?

So judging by dummy experimenting the bolt staff’s alt fire has 3 levels of power. You get the first level if you fire instantly, the second if you wait a long moment but not long enough for the sound queue, and then the third if you wait for the sound queue. Each level generates more heat, does more damage, gets a better headshot multiplier, and does better relative damage against armor.
However if you keep holding/charging after the sound queue, you will eventually get another sound queue as if there is a fourth level of charge. When tested on dummies however this fourth level does not increase damage under any circumstances, nor does it increase heat generated.
Does anyone know if this apparent fourth level actually does anything? Is it just a remnant that never got removed or a glitch?
I’ve seen someone suggest it penetrates more enemies, but i’ve been having great success throwing even the level 1 spears at hordes and having them blow through a whole lot of rats so i’m not sure that’s true…

Can’t say i’ve ever had it make a noise for a 4th (3rd noise) charge. I’ve only ever heard it make the charging noise twice when using it myself.

There is a subtler fwoosh noise for charge level 2, and then a louder more obvious “igniting” noise for level 3. However if you continue waiting long enough (like twice as long as for level 3) there is a second obvious (and different) ignite noise (noise #3) as if for a charge level 4.
I’d find it pretty odd if this was different for me than everyone else, especially since the final noise is a different one than the previous.

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