You are correct that Colt is one turn in 14,” because that's what their old tooling was and it's always been that way... The Colts give the best accuracy with wadcutters and 158-gr. lead.
Ruger single-action .357s are 16” and button rifled, because that is what the standard twist is on .35 cal. rifle bores from the people who grind the button rifling heads, and they bought the buttoned blanks from various makers and that's what was available.
Ruger double-action .38 / .357s, Security Six, Police Service Six, Speed Six, GP100 and SP101 are 18-3/4” twist, as are S&W. Reason Ruger went with 18-3/4 inch twist on the DAs is because this is the pitch on the rifling broach cutters and there is only one company that makes them. The 18-3/4 twist gives better accuracy with the lighter +P jacketed loads, 110-125 grain. which most people shoot. For good 50-yard grouping with wadcutters you may need to drive bullets a bit faster than factory to maintain stability.
73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia