Savage Arms Model 220 shot gun

I have a break open single shot Model 220 - it has an interchangeable 20" 20ga barrel and a 30" 12 ga barrel. There is no serial number, but a stamped "Z" (symbol) with an "I O". The 12 ga barrel also has an "A" whereas the 20 ga barrel only has a small "20" stamp. Can anybody help with the history and vintage of this gun? Thank you, ojs5.

If it's a 220 with a Utica address on the barrel then no, there is no way to date it only that it was made before the move to Chicopee falls.

The letters your seeing a just inspector stamps.

If it has a Chicopee address I could date it though.