Is Plan B gun available to upgrade?

[Sir Du30]

My Plan B gun is tier 5 iconic and has 56 damage. I can't remember if it is the same tier and the same damage when I first got it from when I played Kold Mirage mission or not. I believe my level was below 20 when I played Kold Mirage. As the time passed, I'm not sure that my gun's tier or damage went up or it's been like this since the beginning. My question is, am I able to upgrade this gun to have higher damage or not?

[envirovore]

IIRC iconics are able to be upgraded to t5++, if the weapon is in your inventory (not stashed) it should show up under the Upgrades menu in Crafting if it's still pending updates to max tier.