The AH was one of the most popular Graphophones and was manufactured for quite a few years. During that time it went through several variations in both cabinet and mechanisms. The AH was introduced with a leather elbow and an appropriate horn that mated with the leather elbow. Some time during production it transitioned to a brass elbow and shouldered horn that accepted the brass elbow. I don't know if this was done during a particular AH variation or at the introduction of a new AH variation. I suspect the change to a brass elbow was quite immediate with very little, if any, overlap with leather elbow examples but that's an educated guess.
As a collector/restorer, it should be a goal to be as authentic as possible. When I hear the word "convenience" it generally means a path of least resistance which may or may not be towards an authentic restoration. That's a route that is too often taken. The early Graphophone AJ is a good example. The first AJ is a very unique machine known today by collectors as a "top wind" AJ. It was a very unique machine that, without exception, left the factory with a leather elbow. But the majority of top wind AJ machines seen at phono sales have brass elbows. Why? Your guess is as good as mine. The top wind shared few common parts with other AJs. When front mount machines became obsolete they were stored in the attic or basement and parts were separated. Very few top wind AJs have come through time with their original parts. I don't know how many times I've heard an optimistic seller say "It was a common upgrade to use a brass elbow back in the day." Really? Why? You could purchase a cheap clamp for the small end of the leather elbow. After adding a tab of glue the leather elbow could be firmly attached to the horn. Problems solved without buying an expensive replacement horn and elbow. Yes, a horn could have been damaged when the machine was current. Yes, it may have been difficult to buy a leather elbow type horn late in the front mount era so a later horn and elbow my have been the best solution. Unless a seller has provenance I will will always suspect that the path of least resistance was taken when I see a machine that should have a leather elbow with a later horn and metal elbow.
My reply is way too long but it's made with the best intentions.
Jerry Blais