I can comment on a S&W repair. They send out a FedEx 2-day shipping label for the revolver. You box the revolver and send it FedEx to S&W at no cost to you. S&W will ship the repaired revolver back to you, at your residence, and you or someone over the age of 21 will have to sign for it. No FFL ever gets involved. Ruger should pay shipping both ways - I see no reason why they wouldn't with the problem you described. If the tech doesn't offer to send out a shipping label, I'd ask to speak to his/her supervisor, explain the problem and maybe he/she will consent to the free shipping - worth a try if denied by the tech.
If it's just the housing that flew off, I'd just put a little 222MS locktite on the screw and screw it back on the barrel - it won't work loose again. Don't use any other locktite except 222, as you might experience problems when attempting to remove the screw later on, if you use the blue or red type.