Subcalibre Device?

[Oatmeal Savage]

Found on GunsAmerica, are these beasties very common? This fellow is selling four.

http://www.gunsamerica.com/guns/976647868.htm
http://www.gunsamerica.com/guns/976667812.htm

Thanks
OS

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.