Ithaca lengthened the 20g chambers from 2 1/2" to 2 3/4" about 1927. You might review this thread http://www.16ga.com/forum/viewtopic.php?t=1983
And if it can be done, Orlen can do it and do it right
Michael R. Orlen
Amherst, MA
(413) 256-1630
michael.orlen@verizon.net
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