I looked over a nice NID 3E 20 bore about 4 years ago at a gun show- smallish beavertail, pg with cap and red Sunbursting pad, SST, Ejectors- std. flat rib- Dealer said it had 28" barrels, but when I scaled them with my trusty Stanley tape rule- I got 26 & 5/8" each time- and you could see the hacksaw teeth marks faintly in the rib keels at the muzzle-

He was asking $2500 for it- I did ask permission to dis-assemble it- the numerical choke marks on the barrel flats were 3 for the right barrel and 4 for the left- or Imp. Mod and Full- so my guess is- some grouse hunter shortened the tubes to get more open patterns-

Did Ithaca NID's have the wide array of frame sizes as did the Parkers?

"The field is the touchstone of the man"..