All my TIG beads on angle-iron are dull gray - help

I just got my first welder - Miller Dynasty 200DX. I am new to this. I took a 2 day class for TIGing stainless and have been playing on 1/8" thick mild steel flat bar (home depot stuff) at home. I started to get decent looking beads so I started playing with some 1.5" x 1.5" x 1/8" angle iron that I want to make into mobile bases for various garage tools. I cleaned all the mill scale off a piece and ran some beads for practice. All my beads on the angle iron are very dull gray. I can't seem to get even a dull shine on the bead on angle iron like I could on the 1/8" flat bar. The angle iron had a lot more mill scale, but I got it pretty shiny with a scotch brite wheel before trying to TIG. I had the machine set to 140A, 20 CFH Argon, 3/32 ceriated. I also tried more and less gas, and ran with a shorter stick-out, but still dull gray. Is dull gray normal for TIG beads on mild steel? If not, what am I doing wrong? Would a gas lens help this (I don't have that - yet).