So there's this:
Quote:
A nonlicensee may not transfer a firearm to a non-licensed resident of another State. A nonlicensee may mail a shotgun or rifle to a resident of his or her own State or to a licensee in any State. The Postal Service recommends that long guns be sent by registered mail and that no marking of any kind which would indicate the nature of the contents be placed on the outside of any parcel containing firearms. Handguns are not mailable. A common or contract carrier must be used to ship a handgun.
[18 U.S.C. 1715, 922(a)(5) and 922 (a)(2)(A); 27 CFR 478.31]
But you are not transferring. The items will be "in the trust". It's basically like shipping a rifle or suppressor to yourself. Say you want to go hunting in Alaska but want to drive through Canada so you decide to ship your rifle and suppressor to yourself
The suppressor doesn't require notification but the SBR will. You'll also be bound by the requirements of the shipper
*I am not a lawyer