I got really lucky and got a weapon from the vault, later on I got Jotungeirr, Destiny’s Call and BiB wanted me to equip it. I ended up trading it to so I don’t have it now but looking at BiS it is choosing it over my M+ weapon. It also shows up in the Upgrade Finder as 0.64% upgrade.
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I did a couple of sims to see it that matched, as it doesn’t seem right to me, and it’s about 100 dps behind.
6,831 DPS with Jotungeirr, Destiny’s Call
6,927 DPS with my 252 M+ weapon
So for some reason the optimiser logic likes it more than it should.