I believe that as an individual you get a tax-free transfer upon death (Form 5 I believe), so there is that.
However if you want an orderly plan:
Start by looking at a trust:
https://www.silencershop.com/gun-trust.html
Basically you and your trustees can enjoy your NFA items while you're living. Unlike owning as an individual, they can legally borrow it and take it to their farm to shoot.
If "borrowed" across state lines, fill out a 5320.20
And upon your death:
https://www.nationalguntrusts.com/blogs/nfa-gun-trust-atf-information-database-blog/what-happens-when-a-settlor-dies
Your M1A1 is probably worth 25-30K, so it's a chunk of money.