Form 1 is used for people or non-FFL/SOT entities (trust/LLC/etc) that want to make/manufacture their own SBR, SBS, or suppressor not for dealers who are selling NFA items made by others. If you are wanting to make your own SBR or suppressor, you can file a Form 1 but need a trust or LLC to use eForms. If you are wanting to buy an already made NFA item from a local dealer then you are stuck using paper Form 4 as they are not available on eForms and probably won't be until towards the end of the year.
Oh... well that sucks. You'd think that the form used the most would be what they have on eForms...