Well, I'm not so bumish as you thought.I'm able to craft MK 2 armor and grease gun easily.I'm speaking about higher caps cause I need 8000 for 2 levels of gunsmith SM.Thanks anyway
You can only have 4 professions.In your case that would be 3 armorer and 1 SG, 2 armorer and 2 SG or 1 armorer and 3 SG.All depending on what mk2 armor you can craft.Try finding a BoS vs. Remants or NCR army vs. Remnant encounter.Wait till the fight is over and loot.
Sounds like he probably has Armorer 1 and is crafting leather MK 2, and has Small Guns 1. And he wants two more levels of SG.