Converting From AR Pistol to SBR

I currently have a Multi Caliber lower that i made into a 300BLK pistol. That being said, is there a way to legally covert it to an SBR? If so, can I then drop any caliber lower I have onto this receiver (either short or long barrel)?

No. The ATF rules are quite specific on that. A quick Internet search will give you what you need to know.

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Thats the problem…hard to find good information on the internet. Some say you can pay your tax stamp and reclassify the lower as an SBR, but I have not found any specific information on dropping a long barrel on an SBR or it having to be caliber specific.

Well, I did mean a reliable source - the ATF site. I apologize for my error, apparently an answer to that specific question is not readily found on the ATF site.

This pdf from the ATF site covers when a rifle is converted to a pistol, excerpt:
“[I]f a handgun or other weapon with an overall length of less than 26 inches, or a barrel or barrels of less than 16 inches in length is assembled or otherwise produced from a weapon originally assembled or produced only as a rifle, such a weapon is a “weapon made from a rifle” as defined by 26 U.S.C. 5845(a)(4). Such a weapon would not be a “pistol” because the weapon was not originally designed, made, and intended to fire a projectile by one hand.”

I could not find a result on the ATF site that specified pistol to SBR. I did find this that stated converting a pistol to an SBR requires an NFA tax stamp, but I could not confirm that on the ATF site. You have two options, contact the ATF with that question, or don’t even consider converting it.

“If you take your handgun and turn it into an item that is designed to be fired from the shoulder, and it doesn’t meet the 16-inch-barrel-length requirement or 26-inch overall-length requirement, you have created an item that meets the definition of a short-barreled rifle. This item will need to be registered with the ATF and have a tax paid before conversion, just like the rifle to short-barreled rifle conversion.”

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The treating as if you’re converting from a rifle to sbr sounds like a reasonable way to go, because either way you are creating a SBR. The rules don’t seem to care whether from a rifle or pistol.


Not sure I understand this part of your question.

Are you asking if it is legal to use any and all compatible uppers, regardless of barrel length and/or caliber on your SBR lower, once it is registered as an SBR? For example, is it legal to use a 20" barrel 5.56 upper on an SBR lower?

I cannot help you with the question, but you have the right group responding, short of @Craig6. Hopefully he will chime in when he logs on.

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Apologies for the two part question, but you are correct on the second half. From all the great answers here and internet searches, it seems I can convert my pistol lower into an SBR via a form 1 and $200 tax stamp. The information is pretty vague on what you can mount on the lower once it is registered as an SBR. Thanks

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:dash: POOF!! :dash: You rang?

@Dan84 You can do the paper work on ANY AR lower you have, I suggest the Best one you have as far as quality goes. Once you are in possession of the tax stamp you can at that point in time make it any way you want it as the lower is now an NFA device. The biggest up side is that you can have a real stock on a 7.5" tubed upper or any other combination that you would like.

You are absolutely correct the ATFE regs. say very little about what you CAN do with an SBR in the same breath in it’s brevity it says very little about what you CAN’T do. Which means UNLESS it specifically says an SBR CANNOT have X, Y or Z feature then all is legal.

There is some debate about once a pistol always a pistol that follows along the same lines as machine guns so to avoid that I would register a lower that has never been “ANYTHING” or if I HAD to choose (I believe you do on the form) I would make it a rifle lower. Simply because it is Verboten to put a vertical fore grip on a pistol. You can hang anything you want off a rifle. Once that rifle becomes an SBR you can still hang anything you want off the rifle and attach a 7.5" tube or anything else because it is a short barreled RIFLE. I don’t know that the above has ever been litigated but I would hate to be the first.

Bonus Info: While in possession of your SBR you must also be in possession of a copy of the tax stamp/ppwk. Look at getting a B-5 or SOPMOD stock that has the two “battery compartments” built in. Rolled up paper fits wonderfully and the stock is comfortable as all get out. A bud of mine with an SBR/Can at a “unofficial” competition almost got hemmed up by local LEO because his truck with the gun case and paperwork was 3 miles away. Fortunately the fella running the comp knew the Sheriff and the faux pas was let go at a warning but the point was made. Keep the minimum ppwk required in or on the gun.

Hope that helped.




I can answer a couple of things for you. Your lower is what will be registered (I assume we are talking AR style?). You will have to specify the caliber. That info will be on the tax stamp. The overall length of the SBR will also be on the paperwork. Meaning if you have a X inch bbl and overall length of X inches that will also be on the Form 1. Your lower will have to be engraved with your name and city/state and caliber if it is not specified on the lower. You don’t have to carry your stamp paperwork with you but it would help should a BATF agent ask to see it, long story don’t ask. It must be available for them to see but does not specify where it will be kept. You can’t take it out of state unless BATF is notified. Lots to consider.
Edit to add:You can keep NFA stamp info on your phone should a question arise.

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Dan, I think the easy answer is, NO…DON’T!!!

You’re crossing into that area that will only get you in a LOT of trouble. Speak to your local gun stores and ask them if you can buy an SBR…they’ll probably show you the laws on them.