Not a large sample, but what I have:
Remington A grade damascus at 3" .121" - .123" just before to the thinnest in the burst bulge of .110" = about 9%
Parker Special Steel at 5" .091" to .080" = about 9%
Smith 20g No. 00 Armor Steel at 12" .038" to .032" - .035" = about 8 1/2%
Winchester Model 12 Nickel Steel mid-barrel: .044" to .038" = about 8 1/2%
Ward & Sons post-1925 unknown fluid steel mid-barrel .025" - .027" to .019" - .021" = about 7 1/2%
Surprisingly consistent %s.
Stan looks to be correct that it IS more than "not much."
