At a minimum, you are going to need a new tax stamp for the transfer. My main areas of concern here wouldn't be ATF but IRS. There are probably tax implications involved in the transfer that have to be correctly reported and between the state sales tax, state franchise tax, and federal income tax, you've got several different layers of possible missteps and subsequent fines and penalties. The higher the value of your NFA inventory, the more you need to think about this.
In forming a trust, the big issue is how many people are involved and how many of them have or may have an incentive to sue you or the trust. A large, valuable NFA inventory creates more lawsuit potential than a single .22LR suppressor. The smaller the number of people involved and the smaller the value of property, the easier it is to rely on a form/software. This is the one big advantage of the LLC, it is always going to be one person. In a trust however, you have a minimum of at least two parties due to the nature of a trust.
Typically, you will be the settlor (person who gives property to the trust) and trustee (person who controls/manages trust property). So the issue you want to consider carefully is who is your beneficiary? If it is a spouse, you need to consider what might happen in the event of divorce, which is an area most form trusts handle poorly or not at all. It is relatively simple to create legal problems for yourself with a form trust; however, most people will never realize they created a potential problem because it will never end up in court to begin with. If you are not comfortable with that level of unknown risk, then you need to talk to a lawyer who can devise a trust to meet your need. This is even more true if you have a substantial value of NFA items or wish to add other property to the trust.
