to add to James Rogers post , here are some more
In the book, "Flintlock Fowlers", there are 160 fowlers shown. Front sights- yes. Rear sights- no
sorry bob but thats just not the case
there are many . if not most all . but if we just count sights that are above the plain of the barrel
page 34 . NewEngland fowler c 1737.
page 56 . New England fowler c1775
Page 77 . new england fowler c 1790
page 84. new england fowler c 1800
page 156 . hudson valley Fowler c 1760
page 160. hudson valley Fowler c 1770
page 162 hudson vally fowler c 1770
page 164 Hudson Valley fowler c 1785
every fowler minus 2 starting at page 200 through 221and again on 226, 235.
so unless i missed a couple 31 with sights above the plain of the barrel
now if we go back and count those with such sights as James showed in his link or filings center of the barrel . we would have to list most every one that i can see.
sure there are a few that dont but most all have some type of rear reference , thats used for a rear sight.
speaking only of those fowlers showcased in Flintlock fowlers
even today many dedicated shotguns carry rear sights . IE double beads , raised ribs with double beads or a rear bead and a front tube