So call Tina and ask. It would seem to me that Tina would have communication with Sam about the schedule. It is my understanding that usually Sam will tool up for specific tasks like doing tabs just before doing a bunch of refinishing. So you could time your shipment to arrive a week before or whenever Tina recommends to ship to get inline for the next batch.
Recently I have dealt with shipping machine guns. There have been some changes since Covid. DHL will not ship any firearms. UPS will ship Title I but not Title II firearms. FedEx will ship machine guns, but only between SOT FFL holders, and only overnight. The only way, you as a private individual can ship a machine gun, and not lie to the shipper voiding any insurance claim, is through USPS. They don’t differentiate between machine guns, SBR, SBS, handguns, or pistols with a brace. The two designations are concealable and long guns. So to ship your machine gun it must have a 16” barreled upper on it.
To me, the best shipping option is by Registered Mail with insurance. It is the least expensive option of all and should definitely be the most secure way to ship it. I spring for Priority Mail on top of that. It’s only a few bucks more.Good luck with your tab reinforcement project.
Scott