Thanks Pappy.
I took the shotgun to a gunsmith and he used a gauge to check the head spacing: he told me that it is 2-1/2 inches.
He said that he hasn’t work on many Savages but the Browing A5s with 2-1/2 inch head spacing are really old.
He said as far as he knows there are only 2 companies making 2-1/2 inch shells: RST and Fiocchi.
The gunsmith told me that he could modify the gun to shoot 2-3/4” shells: I told him I’d have to think about that.
It seems to me that having it take 2-3/4 inch shells is convenient, but that ruins the character of the gun.
Does anyone know how old this shotgun is?