Went to my metal supplier ... picked up what was supposed to be one sheet of 20ga, and one sheet of 22 ga. Mic'ed them when I got home (an hour away) and it was actually two sheets of 21 ga. about 0.031" jeez it's hard to find REAL 20ga .036" steel.
Ended up buying a couple of square feet from McMaster, exactly .036" which is the same as I found most places on my GTO that I could get a clean reading with a Mic.
One of the problems seems to be most of the metal these days is coming from foreign sources that use metric thickness so US suppliers are just ordering as close as they can to US gauge sizes. Pretty sure even the Canadian stuff is actually metric.
Next time I'm down at the supplier I might mic their 18ga and see what they are actually selling ... my guess is it's a few .001 less than actually 18 ga, which would probably make it very close to proper 20 ga.
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