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Unread 04-04-2019, 08:55 AM   #4
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Dean Romig
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Twenty gauge nominal bore diameter is .615"

Admiral Thomas Perry's 20 gauge Damascus DH, a 1908 gun, bores measure .619" and .620" which seem just a whisker oversize, but who knows?

I can very well imagine Parker Bros. may have polished or honed these bores... being Damascus they may have had minor imperfections after the first boring that may have needed a clean-up.

In my experience in the field of Volvos a four-cylinder block would have been fitted with three "C" sized pistons and one "D" due to the fact that the fourth hole was bored with a cutter that had already cut three holes and was dulled to the point that the fourth hole (cylinder) needed extra honing, hence the one larger piston.





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