Multi caliber SBR questions

[BrushyHillGuide]

If you want a AR style SBR with the option of (let's say) a .223 upper AND a 300 BLK upper, how do you approach the Form 1?

If I understand correctly, the lower needs to be labeled "multi caliber" but I'm not sure about the form. I found some old links off google saying that you need to pick a caliber and enter that into 4c and attach a letter to the Form 1 requesting that they "amend the attached Form 1 with the (following) additional configurations." That sounds reasonable but it's an old post and I wanted to make sure it is still accurate?

Also, is it correct that selecting the SHORTEST possible configuration, for fillig out the form 1 is probably best? I've read that it's not problematic to alter the configuration to be LONGER but that it IS problematic to shorten the length from what's on the Form 1.

Advice would be appreciated.

[batman4706]

You fill out the Form 1 for the configuration you intend to make the rifle the fist time. Then once it's approved you can put any caliber/length barrel on it. Do not put "multi" on the caliber. it will be rejected. Put the original caliber IE 30 cal on the form 1.

[BrushyHillGuide]

You fill out the Form 1 for the configuration you intend to make the rifle the fist time. Then once it's approved you can put any caliber/length barrel on it. Do not put "multi" on the caliber. it will be rejected. Put the original caliber IE 30 cal on the form 1.

Thank you for the reply! So, I'm assuming that in the attached letter, talking about different configurations, THAT'S where I list the other caliber - along with the other barrel length?

Now, on the receiver, is it ok to have "multi" on it? So manny makers do that and I would think that the "multi" would cover the various configurations including different calibers?

[T-Rex]

Just pick a caliber and bbl length for your first build.
You don't need to tell them what other configurations you plan to use.
You do, however, need to be able to return the rifle to the registered configuration.

Length does not matter, aside from being <16". You can put any length bbl on it, once registered, shorter or longer.

[Tony M.]

Now, on the receiver, is it ok to have "multi" on it? So manny makers do that and I would think that the "multi" would cover the various configurations including different calibers?

As long as the barrel is marked with the caliber in a 'conspicuous' manner, then there's no need to mark the receiver with the caliber.

[BrushyHillGuide]

Thanks for al the info, fellas!

[TEXMEX]

Just pick a caliber and bbl length for your first build.
You don't need to tell them what other configurations you plan to use.
You do, however, need to be able to return the rifle to the registered configuration.

Length does not matter, aside from being <16". You can put any length bbl on it, once registered, shorter or longer.

You base this statement on what?

[Marsblue]

Just pick a caliber and bbl length for your first build.
You don't need to tell them what other configurations you plan to use.
You do, however, need to be able to return the rifle to the registered configuration.

Length does not matter, aside from being <16". You can put any length bbl on it, once registered, shorter or longer.

You base this statement on what?

This is the understanding I have after talking to my ATF rep. (I'm a licensed manufacturer) Swapping an upper is a temporary/reversible change so by swapping the upper you haven't made a permanent change to the SBR configuration you listed when registering it.