The Model 55 was designed by Jack Purcell, one of the original members of
the Police Ordnance Company, who was at this time working at Interstate Ordnance Co. His Model 55 submachine gun was marketed as the
"Compact SMG" and internally it was much the same as the Ingram Model 6. A few prototypes were made of the Model 55
and it was demonstrated to several Canadian and American police forces, but
never bought by any. It was very simple to manufacture, since the body
consisted of a simple steel tube which the stock could retract in and out
of. It was a mere 24 inches long, hence the "Compact" name. It is unlikely
that any of these submachine guns still exist today.