Hey guys. Looking to possibly buy a 9mm barrel for my Smith and Wesson M&P 2.0 .40 caliber to take it to a 9mm. This is a drop-in barrel swap and doesn't require any modification beyond buying the barrel and 9mm magazines at a local shop. I would be keeping both barrels and using them both. What is the bureaucracy that comes with doing this? I know this means I need to update something with regard to my registration certificate but does anyone have any experience with this?


















































