vtbowman,
The rear sight hole pattern is the same on all the Encore barrels, but the front hole patterns are different, 15" centerfire barrels take two 6-48 screws just like the Contender(you can use front sight from a Contender), but the Encore rifle barrels use one 8-40 screw.....I have never looked at the 15" ML barrel but if it only has one screw hole you should be OK with a set from the 26" barrel.
Mark