So I really wanted to make the skill Duty Calls work both in and out of the UCP. The UCP doubles its base damage bonus, however, so it really gives guns one shot one kill power.
Weapons
You can choose to go completely into the Jakobs theme with an allegiance relic, which is what I ended up doing. Some powerful Jakobs weapons are the Elephant Gun (which is really good thanks to the UCP), the Maggie, and shotguns like the Quad (which are now boosted by the specialist COM.) If you’re out of the UCP and still have the version of duty calls that boosts base damage and fire rate, you may want to go for slow firing Jakobs guns like the damned cowboy, or just completely drop the Jakobs theme and go for other non-elemental-only guns like the Lascaux.
Shield
The Rough Rider. Its pretty damn good. Especially with Axton’s crisis management, which gives +35% damage resist. while your shield is depleted (Ill put 2 and 2 together for you; that’s all the time.) Badass.
Class Mods
Legendary Pointman is alright, because the build doesn’t have much survival. But in order to truly be a non-elemental build, you have to have 11/5, or at least 10/5 in duty calls. This makes your base damage really high and then your crit on top of that pretty insane, so you’ll be looking at a high DPS. So just use a specialist COM and you should do fine if you play it smart and don’t get careless. The vanilla Duty Calls gives +33% fire rate which is okay. I guess.
Grenades
There aren’t any. It’s Jakobs. If you wanna drop the Jakobs theme, you can pick up a Dahl.
Relics
Among the relics I took a look at included a vitality relic (for survivability), Captain Blades Otto Idol, a Deputy’s Badge (UCP specialist COM boosts shotguns, so you could use this to make a build out of some non-elemental shotguns.) The sweet pick is
the Jakobs alliegance because it makes your guns awesome, but the sensible one is probably a relic that makes you a bit more tanky.
Skills
What I decided to do was pretty risky, but it ended up working. I didn’t want to use any elemental guns, so I just stopped using slag and the guns ended up being powerful enough to still perform well in a mobbing scenario. I wouldn’t recommend it for raiding though. So with that, I skipped Double Up and went for the other 2 capstones, those being Gemini and Nuke. I guess if you really want to make this an actual decent build and not just a meme, cheat a little and use a slag transfusion grenade to make you a bit more survivable and help against the bigger enemies.
https://bl2skills.com/patch/commando.html#55001150005550015505150505005051