Nice old Field Grade. According to the serial number chronology in the second edition of Walter Snyder's book, the gun is from late 1920. Is it marked "Smokeless Powder Steel" on the tops of the barrels? The only Flues-era Ithaca Gun Co. catalogue I have that mentions chamber lengths is the last one, 1925, and it states 12-gauges are regularly chambered for 2 3/4 inch shells.

19n24 vintage 20 ga Ithaca Flues
 

These 20's are still out there. They may not be as pretty as another double, but they're affordable,:whistle: very durable and a good buy for a backup gun or other.

It is indeed marked smokeless powder steel. My chamber length gauge says it is 2 3/4'' but I take it with a grain of salt as I made it myself.

Eldon, get it measured with a good gauge. You'll know for sure. I don't think the early ones were all made in 2 3/4 " chambers. My 20 wasn't. But there's plenty of metal in these guns. I had Les Hovercamp measure the wall thickness and call me before he did any lengthening of the chambers to be sure.

Up through the first Ithaca Gun Co. NID-period catalogue, 1926, they state their 20-gauges are regularly chambered for the 2 1/2 inch shell. Beginning with the 1927 catalogue they give their standard 20-gauge chambering as 2 3/4 inch.

flues guns are solid old guns, but were designed for black powder pressures. so keep your loads light or the wood will most likely crack.