This is my 1st time on the forum and I looked for info pertaining to my project but didn't find what I needed. I have read over the NFA and ATF regulations but I still am not sure, so here is my question. I have a 20 gauge barreled receiver. What I am wanting to do is turn it into a .357 pistol that will look similar to the Remington XP-100. My plan is to cut the barrel off right in front of the chamber. Then I will use a 20 ga to .357 chamber adapter to convert it. At this point it will be a one hand fired pistol after I fit the action to my frame. Problem is that if the chamber adapter is removed it will still fire a 20 gauge cartridge. Don't want to do that but is that a problem since there are legal shotgun pistols. How about permanently attaching the adapter so it can't be removed or modifying the chamber, for example boring it straight and cutting interior threads to accept a threaded pistol barrel. How about if I just use the receiver and make my own bushing to accept the pistol barrel? Bottom line is what would I need to do to keep it all legal? Don't think I would like prison life.