I have a mid 70's japan win 101 special in 12 gage, screw in chokes and 26 inch barrels. Shoots like a dream and I haven't had any problems with factory loads or my reloads. Sorry all of that was me bragging about my gun, I was wondering if you can change the barrels to 20 gage, what would need to be done, if it could be done and if so where would you find a set of 20 gage barrels. I ask because my son would like to shoot my o/u but the 12 gage is a bit much and I would like to have interchangeable barrels. It may be cost prohibitive but was wondering if it could be done. Thanks for any help.