So heres what i found so far from testing a maliwan incendiary viper:
So the base is standard skin, no scope, and a baseline magazine.
Every variation of barrel on the RV body makes the sound im looking for, with the ecception of barrel 4. The damage barrel makes a dinky sound no matter what body its on.
Every variation of barrel on an AX body makes the dinky sound, with the ecception of barrel 1, the baseline.
So next i changed the skins all to maliwan c
This made it so on the RV body, barrel 5 and barrel 2 started making the dinky sound as well as barrel 4.
No change to how barrel 4 sounds on every body.
On the AX body, the baseline barrel started making the dinky sound.
So next i tried giving them all the 2 shot mag.
It changed all barrel variations on the rv body to a third, deep revolver sound that i think sounds the best. Same for the AX body.
One last change to mag 4/material 1 and i think i have my theory ready.
Just as i suspected, no change from the first test. At first i thought rarity is the main determining factor, but then i realized it was damage. Seeing as the gun is level 25, Nothing over 131 damage makes the default visceral cracking sound, and nothing under 132 makes the secondary dinky sound. Ive only been able to get revolvers to make the third sound by adding the 2 shot, which adds 50% damage. Keep in mind, this is only in relation to maliwan incendiary vipers, so it could vary by brand/names.
I was able to make barrel 4 have the default sound by lowering its damage with the mag 1 also, so that further proves it.
Just tested prefix/titles, as far as maliwan revolvers go, its not them either.