I do this quite a lot as I take classes out of state, and to me it is the biggest turn off against getting an SBR.
I send them in bulk every year, at the same time - typically in April or May. The forms are pre-filled on my computer and backup drives, using the addresses of gun ranges, training centers, or hotels. Date range is Aug 1, 202X - July 31, 202X. All I have to do is change the year, print, and sign. I add another state each year. At this point, I am covered from the Pacific ocean to the Mississippi river, Mexican border to Canadian border, with only a few exceptions (places that I don't want to visit, and, if I did, I would never be taking an SBR).
Takes about an hour of my time and $2 in paper, ink, and stamps.
It is not difficult or time consuming, and I only have to do it once a year.
You don't need a new F20 for every trip. You just need one for each state you travel to/through, each year.
This was several years ago, things might be different today. Other people (some here) have had different wait times, some, considerably less. There seems to be no way to predict how long long it will take, accurately. Every case can be different.
I obviously find the "but I have to wait" argument to be invalid, since I have done the F1 and F4 wait several times and have an SBR waiting on an eF4 right now. And, yes, my wait times were quite variable - from an F1 at 45-ish days, to an F4 over 13 months, to multiple bad F3s that prevented me from even
starting the F4 wait for 17 months.
The argument, to me, is just a weird form of mental self-flagellation; and an excuse for people that like to complain.
"This thing that I really want will take time to get. Therefore, I am not going to try. But I will continue complaining about wanting the thing, but not being able to have the thing, because it takes time. In addition, I will spend time, money, and energy trying to find an ineffective substitute for this thing that I want. I will not admit it, but I know that by the time I give up on the substitutes, I will have spent more time and money dodging the wait than it would have taken to get the real thing to begin with."
That fluster-cluck of F3s and the delayed F4 were a pain in the butt and I still don't have that SBR in my possession. By the time the F4 gets approved, it will probably be 2 years of waiting. That is a bunch of suck, and I really wish we had a better process (and that the seller didn't screw up the F3s so many times and so badly).
But I guarantee one fact: In the end, I will have another SBR and the "but it takes so long and I don't want to deal with it" people will still be beating the same drum and complaining that the (normally shorter) wait is too long.
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As for the 14 month wait to transfer the rifle, to get rid of it... That is the game that one signs up for, when playing with these toys. But it is dumb, if someone is in a hurry.
There are quicker solutions as a seller. The quickest of all is to remove it from the NFRTR. Reconfigure the firearm into a non-NFA configuration (pistol, rifle, whatever), send the NFRTR removal request to the ATF, and cancel the engraving (if desired or required) when the response comes back. Typically takes a few weeks.
Any potential buyer pays the same amount for the tax stamp, whether F1 or F4; and if they want to re-SBR it, the F1 will probably come back faster than the F4 would have.