I suspect some of these clips were made for French diameter tubing. The difference in circumference (28mm vs 28.6mm) is about 3mm. I had to use a longer bolt to fit mine.
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My collection: 1947 Ciclo Piave, 1955 Liberia, 1969 Colnago Super, 1972 Legnano Olimpiade Record Specialissima, 1980 Mercian Vincitore, 1983 Gitane Interclub, 1985 Peugeot PGN10, 1985 Eddy Merckx Corsa, 1985 Hood Cycles Lo-pro, 1986 Bianchi Vittoria, 1987 De Rosa Professional, 1989 Vitus 979, 1989 Bianchi Super Leggera, 1990 Bianchi Axis, 1990 Specialized Sirrus, 2001 Colnago Dream B-Stay, 2007 Trek 1000