So hard to tell sometimes
Just what is legal and what isn't. Gun laws can and do change. Seldom for the better from our point of view, but sometimes it happens. The GCA 68 was amended by the FOPA in 86, removing some of the restrictions. But we also lost on that one because of the amendment ending future machinegun registration. Greatest good for the greatest number, but lots of people are still upset at what we lost to get some good elsewhere.
You legal beagles out there correct me if I get it wrong, but as I understand it, currently,
Sale of handgun between residents of different states must go FFL to FFL.
Sale of handgun (by FFL) to out of state resident must go to FFL in purchaser's state.
Sale of hangun to out of state resident, private, face to face, not permitted.
Sale of long gun to out of state resident, private, face to face, not permitted.
Sale of long gun by FFL to out of state resident permitted face to face, if purchaser is resident of contigous (bordering) state. Otherwise, must go FFL to FFL
and, (not completely sure about this one) sale of a firearm by out of state resident can only go to FFL.
As to the original question, how many times does it take for BATFE to decide you are "dealing"? How many licks does it take to get to the center of a ...well, never mind.
Our man here has 15 guns he would like to buy and sell. Buy them all at once, fine. Sell them all at once, maybe not fine. Sell them one at a time, maybe fine, possibly not. All up to the Feds. If they think they can make a case, they will. It is all in how it is interpreted. Sell 15 guns once, you could be a collector selling part of his collection once, or you could by illegally dealing in firearms 15 times! One count for each gun.
I can't say how the Feds might look at it, so why risk it. Key things to consider are buying with the intent of resale (profit), and number of times you do it.
The reason the number is important is that determination is not set in law, it is governed by BATFE rules. Which do change.
At one time the Feds went after custom rifle builders, guys who made everything from scratch. They wanted them to pay the same license fees as Colt, Remington, Winchester, etc. A huge amount for a small business. Feds claimed making (and selling) more than 10 rifles in a year made you a manufacturer, the same as the big boys. I can no longer remember how this mess worked out, but I do clearly remember they shut guys down, even siezed their assets and took them to court.
They had a similar outlook on dealing at one time. Selling a few guns a couple of times a year without an FFL was enough for some people to get charged, ruining a few lives and bankrupting others. They have done it, they can still do it. Whether or not they do it to you depends on their judgement. Don't risk it.
Buying the guns for your self, keeping them long enough for a reasonable person to believe they were not bought for the purpose of resale would seem to be the best course.
How long is that? I don't have any idea. A year and a day? 6 months? one month? I can't say. One weekend, take it out and shoot it, and decide you don't like it, so you sell it. Reasonable to me, but to the BATFE? Only they can say.
If you ask them,
and get an answer, get it in writing, on official letterhead, with the answering agent's name and position clearly ledgible. Don't settle for a phone call, or an e-mail. You might wind up having to produce it in court.
I hate to be a killjoy
and this is a worst case situation, but it is better not to get in a questionable position in the first place than to have to defend your actions in court.
My advice still stands, if the guns are at great prices, and you can afford them, buy them. You can get your money out of them later if you want, without real legal risk, as long as they aren't bought for resale, and you don't make a habit of it.
Good luck.