4 ms·Yes, plus making twisted landings is tough. Akin to threading the inside of a pipe.by CapitalistCartr 10y agoYes, plus making twisted landings is tough. Akin to threading the inside of a pipe.Someone 10y agoWikipedia: https://en.m.wikipedia.org/wiki/Rifling https://en.m.wikipedia.org/wiki/Riflinggonzo 10y agoIt's not that tough. Cutting rifling with a button is done at home from time to time. https://www.youtube.com/watch?v=ihPFjuxBjPo https://www.youtube.com/watch?v=ihPFjuxBjPo