Bullet Biter available in the great vault, but it doesn’t look like it’s in the AMR database yet.
iLevel 649
If it is in your vault it should show up in the great vault search under upgrade finder, or if you own it Best in Bags will show it and try it in combinations.
I can add a drop location so that you can pick it and see it in other places.
I can’t see it in the list of BIS to compare or add it via the add to bags option. It’s still in the vault because I can’t tell if the upgrade ranking is correct versus the other options.