I am looking into building a SBR and had a quick question about applying for the tax stamp as an individual vs. via a trust. Once complete, I intend to keep the SBR in a gun safe which I would like my wife to also have access to. From what I understand, the best way to do that and remain within the guidelines of the law is to have the SBR registered via a trust where both my wife and myself are trustees. Is this correct or have interpreted things the wrong way?

Yea your right.
Would she ever want to take it to a range without you?  If you answered yes, then go the trust route.
If you answered no, then go the individual route..... as long as your always with the sbr, anyone can use it.

What I don't know, and would like to know, so hopefully someone can answer, is....say you did the sbr as an individual, but were not home and your wife used your sbr in a HD situation, how would this work?

This is my primary concern. I don't think she'd ever care to take the SBR to the range without me, but I would like her to have access to the safe in case she needs to get into the safe and grab a handgun / shotgun / rifle / etc., not even necessarily the SBR.

Yea I kinda figured that after I started writing my response

I'm waiting on my first individual stamp right now, I went the individual way to avoid the trust issue(and my CLEO will sign anything) but I figure the sbr would be the worst gun in my safe to fire in the house(loudness), so my fiance knows that in the future, that would be the last gun to grab for HD.  So to me its a nonissue, but I still would like to know the answer.

We have been legally owning NFA firearms as individuals since the NFA was signed into law. We have also been married and lived with our wives and husbands in the same house while simultaneously owning these NFA firearms for the same very long time. If there's ever been a constructive possession case against a wife for possession of her husband's NFA firearm simply by living in the same house or knowing the combination to the gun safe, then I certainly can't find it. And I've looked high and low for it. This is not a reasonable or realistic legal liability, even if she were to use it in a legit home defense shooting.

Now your wife taking it to the range by herself, this is definitely outside the boundaries of any legal protection, stated or implied. If this is something she'd want to do, then a trust is the best option.

If you want to talk yourself into doing a trust, just do it.  No need for validation.  Find a lawyer. Pay him and follow his instructions.

There is no black letter law or case law for the scenario you pose.  It is all speculation.

For me, I have always done individual because I've always been able to find a CLEO willing to sign.  If I couldn't, I'd do a trust.  Game over.  

Yea thats how it is for me, but like I said, I just did my first form 1, but now I know in the future my CLEO will sign anything, so for me its beneficial to just stick with individual.

Homeinvader's post helped me though!  Hope it helped you too OP.