Sig MPX

Status
Not open for further replies.

gregp74

Member
Joined
Jun 27, 2015
Messages
637
Location
Rockford, IL
I'm actually trying to *avoid* an NFA weapon, but I wasn't sure where to post this.

I went to pick up a cowboy lever gun last week and saw this Sig MPX Tacops on the wall. It was screaming my name and I ended up breaking down and getting it this weekend.

I took it out the other day and it's load of fun but got me thinking. Is it possible to put a longer barrel on there and permanently weld/pin a fake suppressor and allow the use of a regular collapsing stock without turning it into an SBR? Or is that just a dumb idea and I should stick to having fun with it as-is?
 
I can't tell if you intended to post a picture or not, but I think that model is the 4.5" barrel with a faux suppressor that brings it to about the same size as the old model with the 8" barrel? I think the basic question would then be can a gun manufactured as a Title I pistol be lawfully made into a Title I rifle configuration?

The internet is full of this discussion, and the consensus is yes, you can. It gets murky as to whether you can legally convert it back (probably?), and there are also questions of constructive intent and possessing parts that can be assembled into an NFA-regulated configuration, i.e. if you own a Sig MPX pistol receiver not registered as an SBR and also own a compatible buttstock, or you own a AR-15 receiver listed as a rifle and also own a pistol-length upper receiver.

This gets murky because if you own a separate AR-15 pistol on which the pistol upper is mounted, that would be fine, but if you only owned AR-15 rifle receivers, you could get in trouble for owning that pistol upper that fits onto the rifle lowers without having a pistol lower.

Does it make sense? No, not really, but it's ATF's effort to issue regulations to execute the nonsensical laws that our legislators have at various times passed, and I actually don't blame them. Sucks when your job is to promulgate rules that make sense based on laws that don't.

I am NEITHER A LAWYER NOR AN NFA EXPERT.
 
I think the basic question would then be can a gun manufactured as a Title I pistol be lawfully made into a Title I rifle configuration?

The internet is full of this discussion, and the consensus is yes, you can. It gets murky as to whether you can legally convert it back (probably?)
It’s not murky: if a firearm started off as a pistol, it can be switched between a Title I rifle and pistol configuration at will. See US v Thompson Center Arms Co and also ATF Ruling 2011-4.
 
Is it possible to put a longer barrel on there and permanently weld/pin a fake suppressor and allow the use of a regular collapsing stock without turning it into an SBR? Or is that just a dumb idea and I should stick to having fun with it as-is?
Yes. You can take a pistol and convert it to a rifle and back again. Just make sure that while you have a stock on it you also have a barrel that’s 16+” inches long. Anything pinned-and-welded on the end of a barrel is considered permanent (even though it’s not permanent to a competent gunsmith) and therefore counts towards barrel length. The legal way to measure barrel length is from the breech face with the bolt closed to the end of the barrel (or whatever is permanently attached to the barrel).
 
It’s not murky: if a firearm started off as a pistol, it can be switched between a Title I rifle and pistol configuration at will. See US v Thompson Center Arms Co and also ATF Ruling 2011-4.

That’s what I was thinking. IIRC someone I knew bought a new stripped lower a couple years ago and the shop advised him to declare it as a pistol rather than a rifle when doing to paperwork just for that purpose.
 
IIRC someone I knew bought a new stripped lower a couple years ago and the shop advised him to declare it as a pistol rather than a rifle when doing to paperwork just for that purpose.
If you’re referring to the federal paperwork, that shop messed up. You can’t “declare” a receiver anything but a receiver on the 4473 since that’s what it is; the 4473 is a transfer document not a registration document and therefore the dealer is required to list the firearm as it’s currentlay configured, not as the customer plans to configure it in the future. A receiver can’t be transferred as a pistol or a rifle since it doesn’t meet either of those definitions under federal law: even if the receiver has a stock on it it’s still not a rifle. (Obviously, state laws might allow a dealer to sell a receiver as a pistol or a rifle on any supplemental state paperwork, but that wouldn’t affect the federal paperwork.)
 
Last edited:
If you’re referring to the federal paperwork, that shop messed up. You can’t “declare” a receiver anything but a receiver on the 4473. It can’t be sold as a pistol or a rifle since it doesn’t meet either of those definitions under federal law: even if the receiver has a stock on it it’s still not a rifle. (Obviously, state laws might allow a dealer to sell a receiver as a pistol or a rifle, but that wouldn’t affect the federal paperwork.)

I probably got the details wrong there. It’s been a couple years. Something about doing it as a pistol first. Perhaps they were taking about actually assembling it and not just the paperwork.
 
I probably got the details wrong there. It’s been a couple years. Something about doing it as a pistol first. Perhaps they were taking about actually assembling it and not just the paperwork.
Maybe, but I wouldn’t be surprised if you got your details correct. An alarming number of dealers are ignorant and think it’s possible to list a receiver as a pistol or rifle on the 4473. It seems like every month or so we get a post here about a dealer trying to do that, even though the ATF sent out an open letter to every FFL way back in 2009 telling them how to properly sell a receiver. And if they missed that letter all they’d have to do is read the instructions on the 4473 itself.
 
Maybe, but I wouldn’t be surprised if you got your details correct. An alarming number of dealers are ignorant and think it’s possible to list a receiver as a pistol or rifle on the 4473. It seems like every month or so we get a post here about a dealer trying to do that, even though the ATF sent out an open letter to every FFL way back in 2009 telling them how to properly sell a receiver. And if they missed that letter all they’d have to do is read the instructions on the 4473 itself.

I've never bought just a lower. How does that work on the 4473? Just state that it's a lower and you take it home and build what you want?
 
I've never bought just a lower. How does that work on the 4473? Just state that it's a lower and you take it home and build what you want?
On the 4473 the dealer marks the box for “other” on question 16 (instead of “handgun” or “long gun”), then writes “receiver” in box 27 for firearm type. A lower receiver can be built as a pistol or a rifle. However, if it’s first built as a rifle it can’t go back to being a pistol, but if it’s first built as a pistol it can always go back and forth between a pistol and rifle configuration as the owner desires.
 
I'm kinda going through this my self currently. I have a Aero Precision lower that a bought a few years ago and did nothing with. Now that I have a suppressor in Jail I really want an SBR and decided to build out a .300 blackout pistol first while work on the tax stamp for the SBR. I have no clue what the FFL put on the 4473 but from what I have read what is important is how the manufacturer labeled it out of the factory. So I put a quick email into them asking.
 
I have no clue what the FFL put on the 4473 but from what I have read what is important is how the manufacturer labeled it out of the factory. So I put a quick email into them asking.
No, neither of those are important. What’s important is this: What was the actual, real-life configuration of the firearm when you bought it?

If you bought a receiver, then it’s a receiver. Period. It doesn’t matter if the manufacturer or the dealer made a mistake and labeled it as something else, it’s still a receiver. And if it’s a new receiver, it’s a pretty safe bet that it wasn’t first assembled as a rifle.

Think of it this way: If a car manufacturer made a compact coupe and accidentally called it an 18 wheeler, would your state consider it to be an 18 wheeler and would you need a CDL to drive it? No, that car would still be a compact coupe no matter what paperwork mistake the manufacturer made.
 
Last edited:
No, neither of those are important. What’s important is this: What was the actual, real-life configuration of the firearm when you bought it?

If you bought a receiver, then it’s a receiver. Period. It doesn’t matter if the manufacturer or the dealer made a mistake and labeled it as something else, it’s still a receiver. And if it’s a new receiver, it’s a pretty safe bet that it wasn’t first assembled as a rifle.

Think of it this way: If a car manufacturer made a compact coupe and accidentally called it an 18 wheeler, would your state consider it to be an 18 wheeler and would you need a CDL to drive it? No, that car would still be a compact coupe no matter what paperwork mistake the manufacturer made.

That makes sense but in the rare situation where you were questioned if both the FFL and Manufacturer marked it as a rifle how do you even begin to prove it was never assembled as a rifle?
 
That makes sense but in the rare situation where you were questioned if both the FFL and Manufacturer marked it as a rifle how do you even begin to prove it was never assembled as a rifle?
I think “rare” is an understatement. First, I’ve never heard of a situation where anyone was questioned about (let alone charged for) the assembly history of a lower receiver they bought. Second, I’ve never seen (or heard of) a receiver coming from the factory labeled as a rifle. Third, most dealers would still enter it into their books as a receiver anyway, since that’s what it is. And finally, any salesperson who bothered to read the instructions on the 4473 would know that a receiver should be marked as an “other” and a “receiver”, not as a “long gun” and a “rifle” (sadly, this one is less rare than the others).

But let’s pretend that all four of those events actually happened together. So what you’d be tasked with is proving that you bought the firearm as a receiver and not a rifle. Remember, it doesn’t matter if it has been built as a rifle at some point, the only thing that matters is that it wasn’t first assembled as a rifle either by you or by the manufacturer. It’s pretty hard to prove how you first built your receiver unless you have videos or pictures, but I’d think there would be evidence that you didn’t buy a full rifle from Aero Precision, you just bought a lower:

-They come in small boxes, so if you still have the box, that’s evidence you didn’t buy a rifle.
-The receipts of sales from the manufacturer to the dealer and from the dealer to you would be for a price that was much lower than the cost of a full rifle. (And if the dealer wasn’t direct with Aero and bought it through a distributor, that’s a third receipt.)
-Any camera footage from the store or from the parking lot would clearly show you leaving the store with a small, non-rifle sized bag.

My point here is that you bought a receiver and there’s plenty of evidence that you bought a receiver, so I wouldn’t worry about it. People seem to worry a lot about what their receiver was sold as, and it’s due to a common belief that the 4473 “registers” the firearm and therefore a receiver marked as a “rifle” on the 4473 is now a rifle. But that’s not how it works; the 4473 is a transfer document, not a registration document. You bought a new lower receiver from Aero Precision, therefore — according to both the US Supreme Court and the ATF — you can build that receiver as either a pistol or a rifle. Also according to the same authorities, if you build that receiver as a pistol first you can always go back and forth between building it as a rifle or pistol, but if you build it as a rifle first then it can only be built as a rifle. Spending time worrying that you’re going to get falsely accused of a crime because of an extraordinary convergence of mistakes between the manufacturer, distributor (if applicable), dealer, and salesperson is kind of like spending time worrying that you’re going to get arrested for a bank robbery that someone else committed.
 
On the 4473 the dealer marks the box for “other” on question 16 (instead of “handgun” or “long gun”), then writes “receiver” in box 27 for firearm type. A lower receiver can be built as a pistol or a rifle. However, if it’s first built as a rifle it can’t go back to being a pistol, but if it’s first built as a pistol it can always go back and forth between a pistol and rifle configuration as the owner desires.
It is my understanding that in some jurisdictions, the dealer must classify it differently, depending on state/local statutes. Probably only applies to the occupied territories and I live in a free state, so don't take it as gospel. Know your local laws.
 
It is my understanding that in some jurisdictions, the dealer must classify it differently, depending on state/local statutes. Probably only applies to the occupied territories and I live in a free state, so don't take it as gospel. Know your local laws.
No, state or local laws can’t change what the dealer marks on the 4473. Remember, the 4473 is a federal document. If a dealer sells a receiver as a pistol or a rifle on the 4473 then he’s wrong no matter what the state or local laws say.

Now, some states and localities might have extra rules that supplement the 4473, but they can’t change what the dealer puts on the 4473 itself.
 
Status
Not open for further replies.
Back
Top