Most of the Model 97's were chambered for 2 5/8" shells, with a roll crimp. Even those that were chambered for 2 3/4" were still made for roll crimp shells, which are shorter than star crimped shells when fired.
From the 1897's I've inspected ( I own 6, and have inspected well over 100) it appears that chambering was done by hand, since no two appear to have been chambered the same, especially in the forcing cones. Some have long forcing cones, and some have short, with some in between.
For take down 97's, any gunsmith who works on shotguns can lengthen the chamber for you, and polish the forcing cone, since the barrel/slide assembly comes right out of the gun. The problem lies with the solid frame guns. Most reamers won't fit inside the action, so it takes either a reamer that has been shortened to fit, or removing the barrel, which can be problematic for a gun roughly 100 years old.
I've had the chambers lengthened on all my 97's, even my wife's solid frame gun made in 1899. If you've ever noticed that shells fired through an unmodified chamber have the crimps "feathered" after shooting, it's because the crimp is going into the forcing cone of the too short chamber, and is being crushed by the shot column and wad.
These old guns deserve proper care, and chambering them for today's ammunition is the proper thing to do.
Hope this helps.
Fred