I am not sure that all of the facts are on the table here.

Did the OP buy a new gun? Is he claiming to be the original purchaser at retail? If that is the case and the firearm has a defect in materials or workmanship then I would say that there is basis for S&W to fix this and I would approach them that way.

However if the OP purchased a Previously Owned Firearm it is a USED GUN. It does not matter what condition it is in. It does not matter what paperwork was in the box. It does not matter if the previous owner(s) fired it or not, it is just another used gun. Under this situation the OP has no basis to expect a free repair. The OP would not be the person to whom the firearm is warranted.