I believe the 20 gauge NS originally came with short chambers. I have #163xxx (1924) and #191xxx (1925) and both had 2 1/2" chambers. I had one of them lengthened to 2 3/4" and the other I left unchanged. I don't know when Ithaca made 2 3/4" chambers standard on the 20 gauge guns, but I have seen some later guns with longer chambers.
I also have a 16 gauge NS (#288xxx) made in 1929 that has 2 9/16" chambers. I believe Researcher is correct that the longer chambers on the 16s became standard in 1934.
Last edited by Jack71; 02/03/19 05:04 PM.
