Hello all!
There is no doubt that the Ithaca Single Selective Trigger was a direct copy of the Miller. The Ithaca version was known as the "Howland" trigger (named after their designer Harry Howland). The only difference that I can find between the two is that the Howland trigger has a two-piece trigger body as opposed to the Miller's one-piece. There is absolutely no reason for this design difference as far as function goes and I feel it is superfluous and weakens the design. The Howland is still a great trigger though because it is essentially a Miller (but I'm admittedly biased)!
The Millers designed their second generation style of selector because they felt that the safety based selector was a weak design and prone to problems. The reason for this is that the barrel selection is accomplished via a long, thin section of piano wire that ran from the rebound guide to the transverse oscillating trip. If this wire weakens, it can cause the trip to not fully move to its left or right position which can cause reset problems or in the worst case, doubling. The second generation selector (which is a rocker switch located on the front of the trigger body itself) was fully mechanical in operation and very robust. Selection is positive and once moved, it stays locked in position with a ball detent. There is still a section of wire connecting the selector to the trip, but it is much shorter and straight, making it last indefinitely. Admittedly, it takes a little getting used to and is not as easy to select as the safety mounted selector. We just finished a repair of a Howland trigger that was malfunctioning due to the aforementioned spring wire becoming weak. In this case, it was preventing proper reset to the second barrel.
It is nearly impossible to diagnose single trigger problems without getting inside to see what is going on. The problems vary from changes in wood to metal relationships, spring failures and mechanical functions getting out of tune. Many times it is a combination. Our worst nightmares come from well-meaning but unfamiliar gunsmiths "taking a crack at it". Especially when they try to "fix" it by changing the sear angles to increase pull weight to "prevent doubling". Sear relationships are rarely the culprit unless they have been messed with.
We're happy to help with any Ithaca or Miller single trigger problems and we're pretty good with Parker singles and Hunter One triggers as well.
Best to everyone,
Dan
