There have been questions regarding the use of iterating vs non-iterating
Xylophones and Glockenspiels.  Those instruments that have original
equipment iterating Xylophones were designed to use rolls that could also
be used to play another set of pipes thus the difference between that and
the "4-X" rolls that were cut specifically for use on machines with a
non-iterating instrument.  The iterations are actually cut into the roll.

It is for this reason that 'single stroke' or 'non-iterating'  Xylophones
and Glockenspiels don't play properly when used on instruments with "A"
rolls or with "G" rolls.  The reverse also obtains when a "4-X" roll is
used on a machine designed for "G" rolls.  You can always remember, on
the "4-X" roll the 1st additional instrument is usually the single stroke
Xylophone while on the "G" roll the 1st additional instrument is the
first pipe set, usually the Flutes, if there are two sets.

I have played "4-X rolls on the Seeburg in place of the "G" rolls just
for the interest of it.  Later, I played the corresponding "G" roll and
there is a noticeable difference.  I have also played "G" rolls on my
Nelson-Wiggen "4-X" machine and can notice the obvious shortcomings that
way, too.

My suggestion is merely this, play your "G" and "4-X" rolls on whatever
you desire but allow for the differences when you judge the sounds coming
out of the instrument.

Of course, if you have a Xylophone on an "A" roll player it should be of
the iterating type.  I don't know of any "A" rolls that were ever made
for a single stroke Xylophone.

Musically yours,

Hal Davis