Bare aluminum:
After dipping into tri-acid (nitric, sulfuric, and hydrochloric acid mix):
After dipping into 50% nitric acid:
After sitting in the low phos TNB bath for 30min
That is the frame for a $6k Burton gun. Always gives me pause to dip someones gun into tri-acid, but a heck of a lot more when it's worth 6k.
Also, it's fun to pick apart a gun as nice as this one. Excellent work, Jason!