If you want a 20" just buy a longer one (26-30") and have it cut down by a smith, thread for chokes and install you choice of sight. A barrel can be cut down to a minimum of 18.6 inches with out making it a prohib if I understand the laws correctly. If I'm wrong someone will correct me.
OEM 18" barrels are on the EE all the time just keep an eye out for them in the parts and bits EE



























