over the years, i have axed old ed, my go to gunsmith, to lengthen chambers on a variety of 2 1/2" double guns...first thing old ed would do is to measure barrel wall thickness in front of the chambers...never had him declare "too thin" for an american made gun...occasionally, he would refuse to do work, on light weight european made guns, because barrels walls were "too thin"...16 gauge frenchie gons come to mind...

keep it simple and keep it safe...