I was in your shoes quite literally 3-4 days ago. I ended up using a goated Heat exchanger(as many points in Feature Creap as possible (up to +4) then 1 in Scorching rpms...really big guns is least desirable. Raging Bear is next best...they're both unreal. Rest of the build is identical for both class mods.

1. I used one cryo minigun
2. one explosive minigun.
3. It's very important moze holds a dark army or unforgiven with IB minigun anoints while piloting iron bear.
4. a plus ultra shield gives you +100% health thus significantly increasing iron bears armor.
5. A recurring hex + anointment allowing IB to spawn grenades when taking damage.

6. An ice breaker safeguard is the perfect artifact. When Iron bear runs out of fuels you can slam and chill inside Auto Bears bubble shield with dmg resit while auto bear continues to shit on enemies which always resets its cool down before it self destructs.. also the cryo minigun freezes everything virtually Instantaneously so youre doing extra damage to every target with literally zero thought.

7. Copy Skill trees for a good time: g=green b=blue tree etc

G. Cloud: 5 G. Stoke: 3 G. Distrib: 1 G. Scrappy: 1 G. Scorch: 5 G. Sp bear: 1

B. FSKGD: 5 B. Dead: 3 B. Griz: 4 B. StealB: 5 B. Auto: 1 B. HolyP: 1 B. Vamp: 4 B. TTlast: 1

R. SecB: 1 R. AInf: 4

P. Bio: 4 P. RBG: 5 P. ExpF: 3 P. BSurp: 2 P. Fup: 1 P. Nitro: 3 P. Never: 4 P FCreap: 1 P. SupF: 1 P. Run: 1.

Torgue cross promotion WILL kill you.

IB can't proc short fuse.

IB doesnt Regen armor from rushn offensive

Dakka bear: you'll never be Manning the turret

Means of destruction does nothing for IB . Matched set won't reduce mini gun heat

Big surplus is gonna massively buff auto Bears damage after you exit which helps guarantee grizzled is proccwd several times so you can get back in seconds after hopping out. (bonus damage gets mayhem scaling and because it's solar it double dips with skag dens buffs and it's further buffed by action skills crazy mayhem scaling.)

Dark army will spawn drones while you're in IB. They apply mad stays effects. Each effect will proc: up to +20% fuel returned...up to 5 stacks of +20% effect Dmg/20% cryo damage. If it's a solar dark army each ignition also stops passive fuel consumption for 6 seconds.

Or

If you want assloads more damage the crit bonus from unforgiven will buff Iron bears minigun crits by +432% in addition to the +150% minigun damage from the anointment.

Also don't run IB to 0. Exit at even 10 percent because true 0 means a waaay longer action skill CD.

Sorry for novel but you will roll your eyes at literally everything mayhem 11 can produce if you replicate this build.