Take the rifles there, get the $25.00 for them and a receipt, send the $25.00 and a copy of the receipt to your son, and you won't have to deal with this anymore.
Worst idea ever. Then he gets sued for the value of the rifle and potentially faces criminal charges over destruction of private property or the illegal sale of firearms that may or may not be his.
I still think they are his at this point, but I wouldn't risk it. Besides, giving the gun grabbers guns validates what they are doing. Horrible idea.