Usually transfers occur in the context of a retail purchase at a gun dealer. A gun dealer who can handle NFA firearms is called an FFL/SOT ('Federal Firearms Licensee/Special Occupational Tax'), and sometimes they are called 'Class 3' gun dealers. These dealers typically assist customers in completing the Form 4. We provide our clients a user's guide to help them use their Arsenal Gun Trust as Form 4 applicant (the transferee). It's important to ask your gun dealer if they are able to submit your Form 4 using the ATF eFile system in an effort to obtain a tax stamp quicker. Overall this can be an easy process, and there are signs BATFE has begun solving its backlog problems so tax stamps may be issued faster.
Many of our clients own NFA firearms personally, and they wish to transfer them into their Arsenal Gun Trust. Their Trust would submit a Form 4 to transfer the time from the client and into the client's Trust.
You can see a sample Form 4 at this link. When completed a Form 4 you should always confirm you are using the latest version required by BATFE.
When using an Arsenal Gun Trust, you can skip the Form 4's requirements for fingerprints, mug shot, and the signature of your local Chief Law Enforcement Officer ('CLEO').