I recently purchased an Ithaca solid rib, 37R in 16ga that has what I am told to be a factory installed polychoke. A friend advised me that he did not think that any model 37's were made with a polychoke. A check of the serial number with Diamond Gunsmithing in Ithaca NY revealed this particular weapon was made in 1940 and the serial number range isR21xxx. Anyone Ithaca collectors care to offer some insight ?