So, I know a 5320.20 is not necessary for FFLs.

Does that apply only to sole prop FFLs, or do partnership FFLs allow both partners to bypass the 5320.20?

Does it only apply to guns on the books, or is their personal collection also exempt?

I can't find any concrete details on this.

Only guns in your books.

only guns currently registered to the FFL.

as long as your partners or whomever are RPs or whatever the term is on the FFL, it applies to all persons on the FFL.

So they need to be "on the books" - got it.

So putting my personal firearms in the A&D covers them. Any downside to doing this? I can just log them back out as I see fit, can I not?

Anything I'm not thinking of?

Considering the .20 is only needed for certain NFA items, you'd need to pay $200 to transfer them to your business (and another form 4, $200, and year wait to transfer back to yourself). I've kept my personal SBRs/Silencers I had before my FFL out of my books. Anything new since SOT has remained on form 3.

Non NFA items don't need anything special to be transported interstate.

Each time you transfer a firearm from your business to yourself, make sure to do the 4473 and NICS if required. I'd minimize the amount you do this, mainly just for the paperwork of it. Each 4473 is a chance to mess up, so don't do it unnecessarily.

If you're a sole proprietorship, you can just log Title 1s back out.

If your FFL is held by an LLC or other corporate structure that helps protect you from personal liability, then you have to do a 4473 every time a Title 1 firearm is transferred to you.

Title 2 firearms don't transfer willy nilly, they transfer on Forms through NFA Branch with taxes and tax stamps and multi-month delays.

Gotcha, so it needs to actually be registered to the FFL, not just on the books of the FFL. Clear.

I'll just fill out the stupid form.