Hi All,  I wish to retract my comments about the pushrods being the
reason for the different length of the pneumatics.  Though I know from
practical experience that a longer pneumatic will produce more initial
force (all other factors being the same), I can only surmise that the
rationale for graduating the size of the strikers had to do with weight
and/or velocity.

It seems reasonable that a heavier hammer requires more initial force
to get it moving than a lighter hammer.  But whether or not that was
the reason for the graduated pneumatics, I don't know for certain.

Musically,
John A Tuttle
Player-Care.com
Brick, New Jersey, USA