There are a few exceptions for "across state line transfers" for non-licensees but please do NOT consider this as legal advice. Although I have yet to do this, it is my belief that I personally meet the dual state exception based on the following ATF example of dual state residency as related to the Gun Control Act (GCA). The document can be downloaded at the following link:
https://www.atf.gov/file/84321/download
Specifically, "A maintains a home in State X and a home in State Y. A resides in State X except for weekends or the summer months of the year and in State Y for the weekends or the summer months of the year. During the time that A actually resides in State X, A is a resident of State X, and during the time that A actually resides in State Y, A is a resident of State Y."
Currently, I reside in Georgia during the week and live in Alabama on the weekends. Additionally, I spend my summers at the lakehouse in Wedowee, Alabama. In my opinion, I meet the conditions stated in the example and could legally buy or trade for your Sig "during the time I am a resident of Alabama".
Why bring this up, you might ask? I am interested in your Sig, and could offer a decent selection of AR trades and/or cash, or other Sig 40's. However, I have posted this to see and listen to other interpretations of the ATFs example, especially from the knowledgeable Moderators, such as @VHinch, or our resident law and legal experts.
I re-posted the quoted info above soliciting feedback from other members regarding doing a deal with an Alabama Sig Legion owner. I have not moved forward with trying to do the deal, and welcome any interpretations of this particular "dual state residency" example. I tend to err on the side of caution and this example seems to be in a "grey area", so I'll most likely not to do the deal, but would like thoughts from others. I also recognize that the cost of a transfer is pretty cheap compared to a potential legal issue, but the example seems pretty straight forward.