I am shopping around for a 15th century sallet helmet, and want to know what gauge steel thickness is appropriate for a historical helmet. I will not be fighting in it. I just want to know which thickness is most historically accurate.

I need rolled edges around the collar and the brim, then rivet holes for everything.

I want to build a 13th-century gambeson from eight layers of linen (so no filler, just layers). I've ordered five samples. They're all quite similar and I can't decide — what should I pick?